FEN1 (flap structure-specific endonuclease 1)

2010-01-01   L David Finger , Binghui Shen 

Division of Radiation Biology, Department of Cancer Biology, City of Hope National Cancer Center Beckman Research Institute, 1500 E Duarte Road, Duarte, CA 91010-3000, USA




Atlas Image
Figure 1.


Spans 4561 bp; two exons; one intron (Figure 1).


Spliced transcript is 2265 bp in length. First exon is 1-351 bp and the second exon comprises 352 to 2265 bps of the spliced mRNA. The open reading frame spans 1142 base pairs (bp 373-1515).


Atlas Image
Figure 2. Structure of human FEN1.
A. Schematic of hFEN1 organization as determined by primary sequence analysis (Shen et al., 1998). The protein is divided into the N-terminal (N), Intermediate (I), C-terminal (C), and extended C-terminal regions colored in blue, green, red, and grey, respectively.
B. Structure of hFEN1 (1UL1) colored according to region. Note: electron density for portions of the I-region and the extended C-terminus were not observed (Sakurai et al., 2005).
C. Topology diagram of hFEN1 (Horton, 2008) colored according to region. Filled triangles and circles indicate structural elements that are conserved in all known FEN1s, whereas open circles and triangles indicate structural elements that vary between phage and archaeal/eukaryotic FEN1s. Yellow stars indicate the relative positions of the active site carboxylate residues that bind the requisite divalent metal ions.
D. Two-dimensional schematic of the hFEN1 structure (Grasby J, U. Sheffield, personal communication). Note: the amino terminus of hFEN1 (true for other archaeal and eukaryotic FEN1s as well) is structured and resides near the active site.
E. Schematic illustration of hFEN1 and its interaction with a double-flap substrate. The duplex DNA 3 of the cleavage site is denoted as the downstream duplex (cyan). The upstream duplex dsDNA (magenta) is 5 to the cleavage site. The 5-ssDNA flap (brown) likely interacts with the helical arch formed by the I-region (Chapados et al., 2004; Liu et al., 2006; Devos et al., 2007; Nazarkina et al., 2008).


Human FEN1 is a metallonuclease comprised of 380 amino acid residues (Nazarkina et al., 2008). The protein has a nuclease core domain composed of the N, I, and C regions and an extended C-terminus (Figure 2A) (Shen et al., 1998). The extended C-terminus is dispensable for nuclease activity, but is important for protein-protein interaction with partners like PCNA and WRN (Brosh et al., 2001; Brosh et al., 2002; Zheng et al., 2005; Zheng et al., 2007; Guo et al., 2008; Nazarkina et al., 2008; Karanja and Livingston, 2009) and contains a bipartite nuclear localization signal (Qiu et al., 2001). Structural studies show that the nuclease core domain of FEN1 has a SAM-like or PIN-like fold with a mixed beta-sheet buttressed on both sides by alpha-helical structure and spanned by an arch-like structure (Figure 2B and C) (Horton, 2008). Moreover, the N and C regions form the saddle-like structure of the protein that binds dsDNA and provide the amino acid residues that bind the requisite divalent ions (Figure 2D). hFEN1 binds two divalent metal ions (Sakurai et al., 2005) and is thought to achieve phosphodiesterase activity using a two-metal-ion mechanism (Yang et al., 2006; Syson et al., 2008). The C-region contains an H3tH motif and binds the downstream dsDNA of the substrate (Figure 3E). The N-region interacts with the upstream dsDNA. Notably, a hydrophobic wedge stacks on the terminal base pair of the upstream duplex closest to the active site and a cleft or pocket binds to a 3-extrahelical nucleotide. The N and C regions are interrupted by the I-region, which forms an arch that spans the beta-sheet and the active site residues. The arch likely interacts with the 5-ssDNA flap (Chapados et al., 2004; Liu et al., 2006; Devos et al., 2007; Nazarkina et al., 2008).
Human FEN1 is subject to post-translational modifications, which are thought to regulate hFEN1 activities in vivo (Nazarkina et al., 2008). The extended C-terminal domain can be acetylated in vitro by p300 at four lysine residues (Friedrich-Heineken et al., 2003). A mass spec analysis identified K267 and K375 of hFEN1 as in vivo sites of acetylation (Choudhary et al., 2009). Amino acid residue S187 can be phosphorylated in vitro and in vivo by CDK1-Cyclin A, which regulates the S to G2 transition. S187 phosphorylation has been shown to decrease FEN1 activity in vitro, which is consistent with the role of CDK1-Cyclin A in cell cycle regulation (Henneke et al., 2003).


FEN1 is detectable in all proliferative tissues, but barely detectable in non-proliferative tissues (Warbrick et al., 1998; Kim et al., 2000). FEN1 is often overexpressed in tumor tissues (LaTulippe et al., 2002; Freedland et al., 2003; Iacobuzio-Donahue et al., 2003; Sato et al., 2003; Kim et al., 2005; Krause et al., 2005; Lam et al., 2006; Singh et al., 2008; Nikolova et al., 2009). Furthermore, cancer tissues have been reported to exhibit FEN1 promoter hypomethylation (Singh et al., 2008).


The localization of FEN1 in human cells is predominantly nuclear (Warbrick et al., 1998; Kim et al., 2000), but is also found in mitochondria (Liu et al., 2008; Szczesny et al., 2008; Kalifa et al., 2009).
Atlas Image
Figure 3. The 3-flap directs cleavage site specificity. Using double- and single-flap synthetic substrates labeled at the 3-terminus (indicated by the gray star), the predominant cleavage site is observed to change from the dsDNA-ssDNA junction (single flap - F(5)•T) to one nucleotide into the downstream duplex (double flap - F(5)•T3F). Single-flap substrates have a secondary cleavage site one nucleotide into the duplex that is equivalent to the cleavage site on the double flap substrate. Note: similar studies with 5-radiolabelling show that a six-nucleotide product is formed with F(5)•T3F, whereas a 5- and 6-nucleotide product are formed with F(5)•T.


General biochemistry: Human FEN1 can cleave a wide variety of substrates with a 5 to 3 polarity exo- and endo-nucleolytically, albeit with widely varying levels of efficiency (Shen et al., 2005; Nazarkina et al., 2008). Regardless of substrate and cleavage efficiency, FEN1 phosphodiesterase activity results in 5-phosphate monoester and 3-hydroxyl products (Pickering et al., 1999; Yang et al., 2006). Consistent with its in vivo roles, hFEN1 preferentially cleaves substrates bearing a single nucleotide 3-flap and a 5-flap of varying length (i.e., double-flaps) (Friedrich-Heineken and Hubscher, 2004). The 3-flap stabilizes the enzyme-substrate complex and increases subsequent first-order rates of reaction to augment "enzyme commitment" to the forward reaction (Finger et al., 2009). Furthermore, the presence of a 3-flap on the substrate increases the cleavage site specificity, such that the enzyme cleaves exclusively at the nucleotide that lies one nucleotide into the downstream duplex (Figure 3 and 4A). With a substrate lacking a 3-flap, the cleavage on the 5-flap predominantly occurs at the dsDNA-ssDNA flap junction and to a lesser extent one nucleotide into the downstream duplex (Figure 3 and 4B) (Friedrich-Heineken and Hubscher, 2004; Finger et al., 2009).
Okazaki fragment maturation: Cleaves 5-flap bifurcated nucleic acid flap structures generated by lagging-strand DNA synthesis during Okazaki fragment maturation in the nucleus (Liu et al., 2004; Garg and Burgers, 2005; Shen et al., 2005; Rossi et al., 2006; Nazarkina et al., 2008). Deletion of the FEN1 gene in mammals is embryonically lethal (Larsen et al., 2003), but deletion of its homolog in Saccharomyces cerevisiae, RAD27, is tolerated (Reagan et al., 1995). Studies in haploid yeast have shown that the deletion of RAD27 increases rates of nuclear mitotic recombination, point mutation, reversion, microsatellite instability, and frameshifts (Johnson et al., 1995; Sommers et al., 1995; Tishkoff et al., 1997; Kokoska et al., 1998; Callahan et al., 2003; Navarro et al., 2007). In a similar manner, direct-repeat recombination, chromosome loss, and interhomolog recombination were increased in rad27Δ/rad27Δ diploids (Navarro et al., 2007). In contrast to nuclear DNA, rad27Δ causes a decrease in mitochondrial direct-repeat mediated deletion and mitochondrial microsatellite instability (Kalifa et al., 2009); however, the origins of these decreases are not understood.
Long-patch base excision repair: FEN1 cleaves 5-flap bifurcated nucleic acid structures generated during nuclear (Nazarkina et al., 2008; Robertson et al., 2009) and mitochondrial long-patch base excision repair (Liu et al., 2008; Kalifa et al., 2009; Robertson et al., 2009). Consistent with the role of FEN1 in mitochondrial long-patch base excision repair in yeast, rad27Δ mutants accumulate point mutations in mitochondrial DNA (Kalifa et al., 2009).
Telomere maintenance: FEN1 has been shown to be important for telomere stability in yeast and mammalian cells by ensuring efficient telomere replication (Parenteau and Wellinger, 1999; Parenteau and Wellinger, 2002; Saharia et al., 2008) and is essential for telomere stability in ALT-positive cells (Saharia and Stewart, 2009). Furthermore, FEN1 forms a complex with telomerase (Sampathi et al., 2009).
Atlas Image
Figure 4. The 3-flap directs cleavage to ensure that all dsDNA product is ligatable.
A. Schematic illustration of the cleavage products of the double-flap substrate. The 3-flap is red, the last nucleotide of the 5-flap is purple, and the downstream duplex terminal base pair is shown in blue and orange. After cleavage, the purple and orange nucleotides are part of the ssDNA product. For the dsDNA product, the red nucleotide forms a base-pair with the blue nucleotide to create a ligatable nick.
B. In a similar manner, cleavage on the single flap substrate, which lacks the red nucleotide, occurs predominantly between the purple and orange nucleotide to create a 5-nucleotide ssDNA product and a ligatable dsDNA product. To a lesser degree, cleavage also occurs at the nucleotide one nucleotide into the downstream duplex to create a 6-nucleotide ssDNA product and a single nucleotide gap dsDNA product. Note: the substrates used in Figure 3 are static structures (i.e., they do not have the ability to equilibrate as in vivo substrates do). See following references for more detail (Kaiser et al., 1999; Kao et al., 2002; Sharma et al., 2004; Nazarkina et al., 2008).


Member of the Rad2 nuclease family (i.e., close cousin to XPG, EXO1, and GEN1) (Lieber, 1997).



Two FEN1 polymorphisms have been reported to be associated with an increased risk of lung cancer. The first polymorphism is c.69G>A (rs174538:G>A) and resides in the FEN1 promoter region. The second is c.4150G>T (rs4246215:G>T) and resides in the 3-UTR of the transcript (Figure 1). Both polymorphisms are associated with decreased FEN1 expression levels (Yang et al., 2009).
DNA sequencing of DNA from tumors and tumor-derived cell lines has revealed mutations in the FEN1 gene that affect nuclease activity (Zheng et al., 2007). Furthermore, studies have shown that mice from two genetic backgrounds that are homozygous for an active site mutation known to alter enzymatic activity in vitro show an increased incidence of cancer (Zheng et al., 2007; Larsen et al., 2008).

Implicated in

Entity name
Prostate cancer
A gene expression profile comparing normal, primary tumor, and metastatic prostate tissue samples showed that FEN1 expression is up-regulated in primary and metastatic tumor tissue along with other DNA replication and repair genes (LaTulippe et al., 2002). The level of FEN1 expression has also been positively correlated with tumor Gleason score, and thus, tumor dedifferentiation (Lam et al., 2006). Furthermore, aggressive forms of prostate cancer as defined by the ability to form tumors in SCID mice show a five-fold or greater increase in FEN1 expression in comparison to a nontumorigenic clone (Freedland et al., 2003).
Entity name
Pancreatic cancer
Using cDNA microarrays, a global gene expression profile of pancreatic adenocarcinoma identified FEN1 as one of 103 previously unidentified genes that were expressed at higher levels in comparison to normal tissue (Iacobuzio-Donahue et al., 2003).
Entity name
Gastric cancer
Using cDNA microarrays and semi-quantitative RT-PCR, FEN1 was shown to be up-regulated in comparison to normal tissue (Kim et al., 2005). Furthermore, using a cancer profiling array and immunohistochemistry, FEN1 was also shown to be up-regulated in stomach cancer (Singh et al., 2008).
Entity name
Lung cancer
FEN1 levels were elevated in small cell and non-small-cell cancers in comparison to normal lung controls (Sato et al., 2003). Furthermore, using a cancer profiling array and immunohistochemistry, FEN1 was also shown to be up-regulated at the mRNA and protein level in lung cancer (Singh et al., 2008; Nikolova et al., 2009).
Entity name
Brain cancer
Gene expression patterns in neuroblastomas were analyzed using microarrays and confirmed by RT-PCR to show that neuroblastomas with unfavorable clinical outcome express FEN1 at levels 2.7-fold higher than neuroblastomas detected by mass screening (Krause et al., 2005), thereby implying that FEN1 expression level in neuroblastoma could be diagnostic of clinical outcome. Futhermore, FEN1 expression levels are higher in glioblastoma multiforme, primary astrocytoma, anaplastic astrocytoma, and oligoastrocytoma as determined by Western blotting (Nikolova et al., 2009).
Entity name
Breast cancer
A cancer profiling array and immunohistochemistry showed increased levels of FEN1 expression at the mRNA and protein levels. In addition, increased expression is likely due to promoter hypomethylation. Furthermore, this study showed that increased FEN1 expression is positively correlated with advanced or higher grace breast tumors (Singh et al., 2008).
Entity name
Testicular cancer
Western blotting analysis showed increased levels of FEN1 in 14 out of the 17 seminomas (Nikolova et al., 2009).
Entity name
Other cancers
Overexpression of FEN1 at the mRNA level has also been detected in uterine, colon, ovarian, and kidney cancer tissues (Singh et al., 2008). In summary, expression of FEN1 is commonly increased to facilitate cell proliferation in cancer cells due to the pivotal role of FEN1 in DNA replication. However, partial or complete loss of function is also known to facilitate the development of cancer by causing genomic instability in eukaryotes (Navarro et al., 2007; Zheng et al., 2007; Larsen et al., 2008).


Pubmed IDLast YearTitleAuthors
123563232002Biochemical characterization of the WRN-FEN-1 functional interaction.Brosh RM Jr et al
145600282003Mutations in yeast replication proteins that increase CAG/CTG expansions also increase repeat fragility.Callahan JL et al
147181652004Structural basis for FEN-1 substrate specificity and PCNA-mediated activation in DNA replication and repair.Chapados BR et al
196088612009Lysine acetylation targets protein complexes and co-regulates major cellular functions.Choudhary C et al
176933992007Crystal structure of bacteriophage T4 5' nuclease in complex with a branched DNA reveals how flap endonuclease-1 family nucleases bind their substrates.Devos JM et al
195252352009The 3'-flap pocket of human flap endonuclease 1 is critical for substrate binding and catalysis.Finger LD et al
127124092003Heterogeneity of molecular targets on clonal cancer lines derived from a novel hormone-refractory prostate cancer tumor system.Freedland SJ et al
151312552004The Fen1 extrahelical 3'-flap pocket is conserved from archaea to human and regulates DNA substrate specificity.Friedrich-Heineken E et al
158144312005DNA polymerases that propagate the eukaryotic DNA replication fork.Garg P et al
182914132008Comprehensive mapping of the C-terminus of flap endonuclease-1 reveals distinct interaction sites for five proteins that represent different DNA replication and repair pathways.Guo Z et al
128539682003Phosphorylation of human Fen1 by cyclin-dependent kinase modulates its role in replication fork regulation.Henneke G et al
126516072003Exploration of global gene expression patterns in pancreatic adenocarcinoma using cDNA microarrays.Iacobuzio-Donahue CA et al
76180861995Requirement of the yeast RTH1 5' to 3' exonuclease for the stability of simple repetitive DNA.Johnson RE et al
104097001999A comparison of eubacterial and archaeal structure-specific 5'-exonucleases.Kaiser MW et al
196996912009Evidence for a role of FEN1 in maintaining mitochondrial DNA integrity.Kalifa L et al
118258972002Cleavage specificity of Saccharomyces cerevisiae flap endonuclease 1 suggests a double-flap structure as the cellular substrate.Kao HI et al
195969052009C-terminal flap endonuclease (rad27) mutations: lethal interactions with a DNA ligase I mutation (cdc9-p) and suppression by proliferating cell nuclear antigen (POL30) in Saccharomyces cerevisiae.Karanja KK et al
107711012000Gene expression of flap endonuclease-1 during cell proliferation and differentiation.Kim IS et al
157018302005Identification of gastric cancer-related genes using a cDNA microarray containing novel expressed sequence tags expressed in gastric cancer cells.Kim JM et al
95668971998Destabilization of yeast micro- and minisatellite DNA sequences by mutations affecting a nuclease involved in Okazaki fragment processing (rad27) and DNA polymerase delta (pol3-t).Kokoska RJ et al
159228632005Genome-wide analysis of gene expression in neuroblastomas detected by mass screening.Krause A et al
121540612002Comprehensive gene expression analysis of prostate cancer reveals distinct transcriptional programs associated with metastatic disease.LaTulippe E et al
168796932006Flap endonuclease 1 is overexpressed in prostate cancer and is associated with a high Gleason score.Lam JS et al
128610202003Proliferation failure and gamma radiation sensitivity of Fen1 null mutant mice at the blastocyst stage.Larsen E et al
185595012008Early-onset lymphoma and extensive embryonic apoptosis in two domain-specific Fen1 mice mutants.Larsen E et al
90807731997The FEN-1 family of structure-specific nucleases in eukaryotic DNA replication, recombination and repair.Lieber MR et al
185416662008Removal of oxidative DNA damage via FEN1-dependent long-patch base excision repair in human cell mitochondria.Liu P et al
165821032006The DNA-protein interaction modes of FEN-1 with gap substrates and their implication in preventing duplication mutations.Liu R et al
151891542004Flap endonuclease 1: a central component of DNA metabolism.Liu Y et al
174834112007A mutant allele of the transcription factor IIH helicase gene, RAD3, promotes loss of heterozygosity in response to a DNA replication defect in Saccharomyces cerevisiae.Navarro MS et al
187022992008[Flap endonuclease-1 and its role in the processes of DNA metabolism in eucaryotic cells].Nazarkina ZhK et al
195969132009FEN1 is overexpressed in testis, lung and brain tumors.Nikolova T et al
125243342002Differential processing of leading- and lagging-strand ends at Saccharomyces cerevisiae telomeres revealed by the absence of Rad27p nuclease.Parenteau J et al
98892661999A single cleavage assay for T5 5'-->3' exonuclease: determination of the catalytic parameters forwild-type and mutant proteins.Pickering TJ et al
110534182001Cell cycle-dependent and DNA damage-inducible nuclear localization of FEN-1 nuclease is consistent with its dual functions in DNA replication and repair.Qiu J et al
78143251995Characterization of a mutant strain of Saccharomyces cerevisiae with a deletion of the RAD27 gene, a structural homolog of the RAD2 nucleotide excision repair gene.Reagan MS et al
191536582009DNA repair in mammalian cells: Base excision repair: the long and short of it.Robertson AB et al
164640142006Lagging strand replication proteins in genome stability and DNA repair.Rossi ML et al
183948962008Flap endonuclease 1 contributes to telomere stability.Saharia A et al
191370212009FEN1 contributes to telomere stability in ALT-positive tumor cells.Saharia A et al
156165782005Structural basis for recruitment of human flap endonuclease 1 to PCNA.Sakurai S et al
190684792009Human flap endonuclease I is in complex with telomerase and is required for telomerase-mediated telomere maintenance.Sampathi S et al
145620542003Increased expression and no mutation of the Flap endonuclease (FEN1) gene in human lung cancer.Sato M et al
146572432004WRN helicase and FEN-1 form a complex upon replication arrest and together process branchmigrating DNA structures associated with the replication fork.Sharma S et al
96120801998Flap endonuclease homologs in archaebacteria exist as independent proteins.Shen B et al
159541002005Multiple but dissectible functions of FEN-1 nucleases in nucleic acid processing, genome stability and diseases.Shen B et al
190108192008Overexpression and hypomethylation of flap endonuclease 1 gene in breast and other cancers.Singh P et al
78761741995Conditional lethality of null mutations in RTH1 that encodes the yeast counterpart of a mammalian 5'- to 3'-exonuclease required for lagging strand DNA synthesis in reconstituted systems.Sommers CH et al
186977482008Three metal ions participate in the reaction catalyzed by T5 flap endonuclease.Syson K et al
186355522008Long patch base excision repair in mammalian mitochondrial genomes.Szczesny B et al
90081661997A novel mutation avoidance mechanism dependent on S. cerevisiae RAD27 is distinct from DNA mismatch repair.Tishkoff DX et al
102111231998Fen1 expression: a novel marker for cell proliferation.Warbrick E et al
196183702009Functional FEN1 polymorphisms are associated with DNA damage levels and lung cancer risk.Yang M et al
166008652006Making and breaking nucleic acids: two-Mg2+-ion catalysis and substrate specificity.Yang W et al
175895212007Fen1 mutations result in autoimmunity, chronic inflammation and cancers.Zheng L et al
155924492005Novel function of the flap endonuclease 1 complex in processing stalled DNA replication forks.Zheng L et al

Other Information

Locus ID:

NCBI: 2237
MIM: 600393
HGNC: 3650
Ensembl: ENSG00000168496


dbSNP: 2237
ClinVar: 2237
TCGA: ENSG00000168496


Gene IDTranscript IDUniprot

Expression (GTEx)



PathwaySourceExternal ID
DNA replicationKEGGko03030
Base excision repairKEGGko03410
Non-homologous end-joiningKEGGko03450
DNA replicationKEGGhsa03030
Base excision repairKEGGhsa03410
Non-homologous end-joiningKEGGhsa03450
Infectious diseaseREACTOMER-HSA-5663205
HIV InfectionREACTOMER-HSA-162906
HIV Life CycleREACTOMER-HSA-162587
Early Phase of HIV Life CycleREACTOMER-HSA-162594
Cell CycleREACTOMER-HSA-1640170
Cell Cycle, MitoticREACTOMER-HSA-69278
Synthesis of DNAREACTOMER-HSA-69239
DNA strand elongationREACTOMER-HSA-69190
Lagging Strand SynthesisREACTOMER-HSA-69186
Processive synthesis on the lagging strandREACTOMER-HSA-69183
Removal of the Flap IntermediateREACTOMER-HSA-69166
Chromosome MaintenanceREACTOMER-HSA-73886
Telomere MaintenanceREACTOMER-HSA-157579
Extension of TelomeresREACTOMER-HSA-180786
Telomere C-strand (Lagging Strand) SynthesisREACTOMER-HSA-174417
Processive synthesis on the C-strand of the telomereREACTOMER-HSA-174414
Removal of the Flap Intermediate from the C-strandREACTOMER-HSA-174437
DNA ReplicationREACTOMER-HSA-69306
Base Excision RepairREACTOMER-HSA-73884
Resolution of Abasic Sites (AP sites)REACTOMER-HSA-73933
Resolution of AP sites via the multiple-nucleotide patch replacement pathwayREACTOMER-HSA-110373
POLB-Dependent Long Patch Base Excision RepairREACTOMER-HSA-110362
PCNA-Dependent Long Patch Base Excision RepairREACTOMER-HSA-5651801
DNA Double-Strand Break RepairREACTOMER-HSA-5693532
Homology Directed RepairREACTOMER-HSA-5693538
HDR through MMEJ (alt-NHEJ)REACTOMER-HSA-5685939

Protein levels (Protein atlas)

Not detected


Pubmed IDYearTitleCitations
214966412011Human flap endonuclease structures, DNA double-base flipping, and a unified understanding of the FEN1 superfamily.128
156165782005Structural basis for recruitment of human flap endonuclease 1 to PCNA.123
185416662008Removal of oxidative DNA damage via FEN1-dependent long-patch base excision repair in human cell mitochondria.108
183948962008Flap endonuclease 1 contributes to telomere stability.68
155617062005DNA polymerase beta and flap endonuclease 1 enzymatic specificities sustain DNA synthesis for long patch base excision repair.66
196749742009Coordination between polymerase beta and FEN1 can modulate CAG repeat expansion.66
155924492005Novel function of the flap endonuclease 1 complex in processing stalled DNA replication forks.64
146572432004WRN helicase and FEN-1 form a complex upon replication arrest and together process branchmigrating DNA structures associated with the replication fork.62
192184312009Specific synthetic lethal killing of RAD54B-deficient human colorectal cancer cells by FEN1 silencing.54
155569962004The human Rad9-Rad1-Hus1 checkpoint complex stimulates flap endonuclease 1.51


L David Finger ; Binghui Shen

FEN1 (flap structure-specific endonuclease 1)

Atlas Genet Cytogenet Oncol Haematol. 2010-01-01

Online version: http://atlasgeneticsoncology.org/gene/40543/fen1-(flap-structure-specific-endonuclease-1)