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). Here, RB1 is linked to neoplasm.