RB1 and hepatocellular carcinoma: It has been generally believed that the CDK4/6‐RB/E2F axis mediates the molecular activity of palbociclib (Asghar et al., 2015); however, recently, the antiproliferative effect of palbociclib in HCC cells has been examined, and interestingly, palbociclib showed activity irrespective of RB status in HCC cells and tumor xenograft (Rivadeneira et al., 2010).