SLCO4A1 and hepatocellular carcinoma: However, we demonstrated an increase in mRNA expression of other OATPs, including OATP2A1, OATP3A1, and OATP4A1 in HCC clinical samples, compared with that in the normal liver tissue samples [25], while OATP3A1 knockdown in HCC cells was shown to significantly reduce the uptake of NIRF dye.