CDKN1A and neoplasm: Berberine induces the over-expression of CIP1/p21 and Kip1/p27 proteins and downregulates cyclin-dependent kinases (cdk2, cdk4, cdk6), leading to G1 arrest of tumor cells (Eom et al., 2008; Lan et al., 2014; Li et al., 2017b).