SLCO4A1 and ovarian carcinoma: Double staining with an antibody against CK19 (red color), which was previously shown to be highly present in the ovarian cancer cells (Svoboda et al., 2018; Menz et al., 2021), revealed that OATP4A1 (green color) is rarely detectable in cells together with CK-19 but rather in cells that do not express this marker (Figures 3E,F).