ABCB4 and hepatocellular carcinoma: These results demonstrate that gene Crem, frequently amplified in both post-PHx and spontaneous tumors of the Mdr2-KO mice, is expressed in hepatocyte nuclei in correlation with its genomic amplification in murine HCC tumors; human CREM is expressed in the tumor cell nuclei of the majority of evaluated HCCs, and is required for the efficient proliferation of human HCC cell lines in vitro.