THAP domain-containing protein 1, also known as THAP1, is a 213 amino acid protein that localizes to the nucleoplasm and contains one THAPtype zinc finger, a conserved DNA-binding domain. It is a DNA-binding transcription regulator that regulates endothelial cell proliferation and G1/S cell-cycle progression. THAP1 may also have pro-apoptopic activity by potentiating both serum-withdrawal and TNF-induced apoptosis. Recombinant human THAP1protein, fused to His-tag at N-terminus, was expressed in E.coli.