Tumors with intense melanin pigmentation extended throughout the lungs in B16-F10 injected mice, whereas lungs from mice injected with the mixtures of the parental ASIP-null tumor cells and both the ASIP(+) oligo-clonal population and its sub-clonal derivative contained pale tumors, some with reddish-brown pheomelanin-like pigmentation, interspersed among tumors having dark eumelanin, but in greatly reduced amounts compared to parental B16-F10 tumors (Figure 3A). This evidence concerns the gene ASIP and neoplasm.