IGF1R and hepatocellular carcinoma: Moreover, the levels of cleaved caspase 3 and cleaved PARP in sorafenib combined with siRNA IGF-1R group and PPP pretreatment group were significantly up-regulated; however, the level of apoptosis-related protein molecules in IGF-1 + sorafenib treatment group was significantly lower than that in the single drug sorafenib treatment group (**p < 0.01) (Fig. 5 C and 5D), suggesting that IGF-1 stimulation downregulates the pro-apoptotic ability of sorafenib on HCC cells.