SLCO1B1 and hepatocellular carcinoma: This is consistent with earlier reports from other researchers that downregulation in tumor tissue OATP1B1, OATP1B3, and OTTP2B1 expression is markedly reduced in HCC tumor tissues compared to adjacent non-tumorous liver, as shown by immunohistochemistry and mRNA/protein analyses (Wlcek et al., 2011; Billington et al., 2018; Thakkar et al., 2017; Le Vee et al., 2011; Chen Shihan et al., 2020).