IFNG and melanoma: Although IFN-γ reduces cellular growth in vitro, when introduced in vivo along with intravenously inoculated B16 melanoma cells, it induces lung colonization and enhanced expression of class I major histocompatibility complex antigens (Figure 4 right) [46, 48], which are more frequently expressed in advanced melanoma and related to an increased risk of metastasis in primary melanoma [46].