IGF1R and hepatocellular carcinoma: The cell clone formation experiment yielded similar results (Fig. 2E F): IGF-1 (100 ng/mL) downregulated the inhibition of sorafenib (4 μM) on the clone formation efficiency of HCC cells, whereas the inhibition of sorafenib on the clone formation of HCC cells was restored to varying degrees with treatment of IGF-1 (100 ng/mL) + sorafenib (4 μM) + IGF-1R inhibitor (PPP, 100 nM) or IGF-1 (100 ng/mL) + sorafenib (4 μM) + siRNA2 (IGF-1R) (***p < 0.001).