MBP and melanoma: To investigate whether the antifolate activity of MBP could contribute to its antiproliferative effects in melanoma cells, we tested the apoptosis-inducing potential of MBP in the Mel501 cell line pre-treated with the reduced form of folate Leucovorin (LV, N5-formyltetrahydrofolate), a drug widely used to counteract the effects of antifolates [31].