MITF and melanoma: We use a natural, so-called evolutionary model of spontaneous melanoma formation in hybrids of platyfish (Xiphophorus maculatus) and swordtails (X. hellerii) (as reviewed in [26, 27]) and a transgenic model in medaka (Oryzias latipes), where fish expressing the xmrk oncogene from platyfish under the pigment cell specific mitf promoter of medaka develop various types of melanoma [28] (Fig. 1).