BID and cancer: As pro-apoptotic B-cell lymphoma 2 (Bcl-2) family proteins, including BH3-interacting domain death agonist (BID), Bcl-2-associated X protein (BAX) and p53-upregulated modulator of apoptosis (PUMA), are able to sensitize cancer cells to TRAIL-induced apoptosis (20), the present study investigated the expression levels of these proteins.