ARIP4 (androgen-interacting protein 4) was identified in a yeast two-hybrid screen using the human androgen receptor (AR) as bait. It was found to be a member of the SNF2 (sucrose nonfermenting 2) protein family and to have ATPase activity. ARIP4 is able to activate AR-dependent transcription. Targeted inactivation of ARIP4 results in embryonic lethality and reduced growth potential of embryonic fibroblast. These findings indicate an important role in development and proliferation.