TIP60, originally isolated as an HIV-1 TAT-interactive protein, is known to interact with the viral TAT protein that leads to HTATIP polyubiquitination and targets it for degradation. It belongs to the MYST family of histone acetyltransferases (HATs). TIP60 is a catalytic subunit of the NuA4 HAT complex which is involved in transcriptional activation of select genes principally by acetylation of nucleosomal histones H4 and H2A. A co-regulator of transcription factors, TIP60 either promotes or suppresses tumorigenesis. TIP60 is an enzyme that has a role in DNA repair and apoptosis and is thoμght to play an important role in signal transduction.