FAS and hepatocellular carcinoma: In addition, since we have previously shown that salirasib induced apoptosis in preneoplastic liver lesions in a rat model of HCC in vivo through activation of the extrinsic apoptotic pathway [18], we studied expression of cellular FLICE-like inhibitory protein (cFLIP), TNF-related apoptosis inducing ligand (TRAIL)-receptor 1 (DR4), TRAIL-receptor 2 (DR5), tumor necrosis factor (TNF)-α, and Fas by quantitative PCR in our human HCC cell lines.