Retards apoptosis induced by IL-3 deprivation. May function in the response of hemopoietic cells to external signals and in maintaining endothelial survival during infection (By similarity). Can inhibit apoptosis induced by serum starvation in the mammary epithelial cell line HC11 (By similarity). Interacts directly with BCL2L11/BIM, BAK1, BID, BMF and BBC3. Interacts directly with PMAIP1 (By similarity). Interacts with BOP (By similarity). Interacts with ING4 (By similarity). Interacts with UBQLN4 (By similarity). Belongs to the Bcl-2 family.