Our study revealed that overexpression of CACYBP and/or RNF41 had no effect on the total amount of P27Kip1 in HCC cells, but CACYBP overexpression caused increased phosphorylation levels at Ser10, Thr157 and Thr198, and subsequent cytoplasmic retention of P27Kip1, through which CACYBP may promote HCC cell growth and proliferation. Here, CACYBP is linked to hepatocellular carcinoma.