Interleukin (IL) -24 (mda-7), a member of the IL-10 family of cytokines (together with IL-10, -19, -20, -22, and -26), has been discovered in 1995 by subtraction hybridization following “differentiation therapy” of melanoma cells: through treatment with IFN-β and a protein kinase C inhibitor (mezerein) neoplastic melanoma cells terminally differentiate and lose their proliferative capacity. This evidence concerns the gene IFNB1 and melanoma.