iASPP(inhibitor of apoptosis stimulating protein of p53)regulator that plays a central role in regulation of apoptosis and transcription via its interaction with NF-kappa-B and p53/TP53 proteins. Blocks transcription of HIV-1 virus by inhibiting the action of both NF-kappa-B and SP1. Also inhibits p53/TP53 function, possibly by preventing the association between p53/TP53 and ASPP1 or ASPP2, and therefore suppressing the subsequent activation of apoptosis. Highly expressed in heart, placenta and prostate. Weakly expressed in brain, liver, skeletal muscle, testis and peripheral blood leukocyte. Belongs to the ASPP family.