PMAIP1 and neoplasm: However, active effectors (BAX and BAK) or initiator (PMAIP1, BIK and BID) cannot lead to apoptosis in tumours, and these pro‐apoptotic proteins may be sequestered by guardians (BCL2 and BCL2L1) that have more potent enhancer activity to propel the anti‐apoptotic mechanisms.