SLCO1B1 and cholangiocarcinoma: For instance, reduced expression or functionality of the plasma membrane transporters proteins OATP1B1 and OATP1B3 (encoded by SLCO1B1 and SLCO1B3 genes) has been linked to lower accumulation of antitumor drugs in human liver cancer, including hepatocellular carcinoma (HCC) and cholangiocarcinoma (CGC) [27].