ABCB4 and cholestasis: We investigated the effects of Abcb4−/−-induced cholestasis in two distinct models, Abcb4-deficient mice (Abcb4−/−) and HBs overexpressing mice as well as chimera of both, knockout and transgene, on BALB/c genetic background (HBs, HBs/Abcb4−/−).