The HCMECs express relatively low levels of the high-affinity OCTN1/SLC22A4 and OCTN2/SLC22A5 transporters and relatively high levels of the high-affinity OCT1/SLC22A1 and low-affinity OCT2/SLC22A2 transporters compared to the HBMECs and A2780 ovarian carcinoma cells (Fig. 2A). Here, SLC22A4 is linked to ovarian carcinoma.