Other in vitro studies have also shown this antiproliferative effect of piperine in colon, lung, breast and hepatocellular adenocarcinoma cell lines, as a result of inducing cell cycle arrest in the G1 phase and regulating the expression of p21/WAF1 and p27/KIP1 [19,20]. This evidence concerns the gene CDKN1A and hepatocellular carcinoma.