Apoptosis sensitivity of HCC cells towards different kinase inhibitors and TRAIL after downregulation of Mcl-1. Huh7 cells were treated for 24 h with different kinase inhibitors (LY294002, 25 μM; PD98059, 50 μM; PP2, 10 μM; rapamycin, 50 pM; SU5614, 15 μM; and TRAIL, 100 ng/ml). Cells were transfected 24 h before with siRNA specific for Mcl-1 (40 nM, "Mcl-1 siRNA +") or with siRNA specific for green fluorescent protein as a control (40 nM, "Mcl-1 siRNA -"). Apoptosis was determined by FACS analysis according to Nicoletti . Values are means + SD. *p < 0.01, **p < 0.001.