Methotrexate, used in the treatment of several cancers (uterus, breast, and lung carcinomas, certain cancers of the head and neck, and some lymphomas and leukemias), has been described as a substrate of OAT1 (SLC22A6)[101] and OAT2 (SLC22A7)[102]. The gene discussed is SLC22A6; the disease is leukemia.