In HCC, circ-ZEB1.33 sponged miR-200a-3p ensuring the expression of the miR-200a-3p target, cyclin dependent kinase 6 (CDK6) [102], that had an active role in phosphorylating the tumor suppressor protein, retinoblastoma transcriptional corepressor 1 (Rb1), thus promoting the cell cycle enter into S phase. This evidence concerns the gene CDK6 and hepatocellular carcinoma.