ABCB4 and hepatocellular carcinoma: In multi-drug resistance (Mdr2) knockout mice – a liver fibrosis model that progresses to HCC in about 12 months [21, 22] – we observed higher Prrx1 expression in Mdr2 knockout mice than in age - matched controls and a lower expression of Prrx1 in older mice with HCC compared to the younger Mdr mice (Figure S2B).