The SET gene spans 6.81 kb on the genomic DNA. The gene includes 8 exons.

There are four transcript variants: 2863 bp (variant a); 2936 bp (variant b); 2638 bp (variant c); 2562 bp (variant d).

The SET protein is a potent endogenous inhibitor of protein phosphatase 2A (PP2A) that encodes three alternative isoforms; isoform 1 (TAF1 alpha)-290 amino acids, 33.5 kDa; isoform 2 (TAF1 beta) - 277 amino acids, 32 kDa ; isoform 3 - 265 amino acids, 31 kDa.

SET is expressed in a wide variety of tissues such as liver, kidney, pancreas, lung, uterus, muscle, brain, bladder and cochlea. Additionally, SET is overexpressed in numerous cancer types such as AUL (von Lindern et al., 1992), Wilms tumor (Carlson et al., 1998), T-ALL (Quentmeier et al., 2009), B-CLL and B-NHL (Christensen et al., 2011), and AML (Cristóbal et al., 2012).

SET localizes predominantly in the nucleus; in the cytoplasm, it is found both in the cytosol and associated with the endoplasmic reticulum and with plasmatic membrane.

SET is a multitasking protein involved in multiple cellular processes.
Role in apoptosis: SET oncogene inhibits the tumor suppressor NM23-H1, a Granzyme A-activated DNase during CTL-Mediated Apoptosis (Fan et al., 2003). Its role in apoptosis depends on the cellular model since while overexpression of SET induces neuronal apoptosis (Madeira et al., 2005), in AML resulted in decreased caspase-dependent apoptosis (Cristóbal et al., 2012).
Role in cell cycle: Overexpression of SET blocks the cell cycle at the G2/M transition in the colorrectal cancer cell line HCT116, inhibiting cyclin B-CDK1 activity in these cells. SET did not inhibit either cyclin A-CDK2 or cyclin E-CDK2 complexes. Moreover, SET and p21Cip1 cooperate in the inhibition of cyclin B-CDK1 activity (Canela et al., 2003).
Role in migration: SET stimulates cell migration in a Rac1-dependent manner. In fact, reduction of SET inhibits Rac1-induced migration, indicating that efficient Rac1 signaling requires membrane recruitment of SET (ten Klooster et al., 2007). A novel peptide antagonist of SET (COG112) inhibits SET association with Rac1 leading to decreased cellular migration and invasion (Switzer et al., 2011).
Role in nucleosome assembly: SET plays a role in MCPH1-mediated chromosome condensation/decondensation. SET inhibits PCAF-mediated acetylation of histones. In addition, SET also inhibits the histone acetyl transferases CREBBP and EP300. Besides, overexpression of SET has also been shown to inhibit demethylation of ectopically methylated DNA resulting in gene silencing (Cervoni et al., 2002).
Role in regulating AP-1 activity: Expression of SET in HEK-293 cells increased levels and DNA binding of c-Jun as well as the transcriptional activity of AP-1 (Al-Murrani et al., 1999).
Role in neuronal development: SET is a negative regulator of neuronal development (Kim et al., 2010) and it is involved in the pathogenesis of primary microcephaly (Leung et al., 2011) and Alzheimers disease (AD) (Madeira et al., 2005).

Belongs to the nucleosome assembly protein (NAP) family.