PMAIP1 and hepatocellular carcinoma: Based on our observation that Huh7 and Hep3B cells reveal a distinct sensitivity towards apoptosis induction by TRAIL and sorafenib, we analyzed the expression pattern of pro- (NOXA, PUMA, BIM, and BAX) and anti-apoptotic (BCL-XL, MCL-1) regulators in these HCC cell lines.