SLCO2B1 and breast cancer: Kindla et al. also compared the expression and localization of OATP2B1, OATP3A1 and OATP5A1 in paired samples of normal breast tissue and breast cancer tissue, and reported that while OATP3A1 and OATP5A1 are localized in the plasma membrane of epithelial cells of lactiferous ducts in normal breast tissue, these transporters are highly expressed in the plasma membrane and cytoplasm of breast cancer tissues [19].