CDK6 and hepatocellular carcinoma: Studies have shown that heterochromatin protein family 1 (HP1), such as heterochromatin protein 3 (CBX3), blocks cell cycles and promotes the occurrence, development, invasion and metastasis of hepatocellular carcinoma by regulating downstream genes such as p21, cyclin dependent kinase 6 (CDK6) and CD44 (Wang et al., 2021).