Important examples include SLC22A1/OCT1, SLC22A2/OCT2, SLC22A4/OCTN1, SLCO1B1, SCLO2B1 and SLCO1B3 transporters, which have broad substrate specificity and mediate transport of numerous anti-cancer compounds such as irinotecan, paclitaxel, mitoxantrone, vincristine, methotrexate, 5-fluorouracil, platinum-based drugs, imantinib and doxorubicin, reviewed extensively elsewhere [1,2,10,11,12,13,14,15]. This evidence concerns the gene SLC22A4 and cancer.