The L-phenylalanine prodrug melphalan (Fig. 4A), a widely used anticancer drug for the treatment of ovarian cancer and multiple myeloma, inhibited the uptake of L-leucine into human MDA-MB-231 breast cancer cells (81), T24 human bladder carcinoma cells (82) and in hLAT1 expressing Xenopus oocytes (16) providing evidence of binding to LAT1. The gene discussed is SLC7A5; the disease is urinary bladder carcinoma.