RPS6 and hepatocellular carcinoma: In parallel with the downregulation of AIB1 protein, sorafenib inhibited the expression of phospho-p70S6K, phospho-RP-S6, and phospho-4E-BP1 in HCC cells (Figure 2C and 2D), suggesting that sorafenib indeed can inhibit mTOR/p70S6K/RP-S6/4E-BP1signaling.