CASP8 and cancer: marked reduction in the viability of HepG2 and SK-HEP-1 cellsinhibition of the cell cycle of cancer cells (HepG2 and SK-HEP-1) in S phasetumor cell apoptosis (growth of apoptotic bodies and reduction of tumor cell size; HepG2 and SK-HEP-1)increased caspase-3 activity and cytochrome c release, without increased caspase-8 activityinhibition of tumor growth