Surprisingly, we found that JQ1 treatment reduced p21 levels in HCC cells, which is in contrast to previous reports that JQ1 arrests the cell cycle at the G1 phase by upregulation of p21 in non-small cell lung cancer, glioblastoma, MM cells, and acute myeloid leukemia cells [10, 11, 24–30]. This evidence concerns the gene CDKN1A and hepatocellular carcinoma.