S1PR5 and melanoma: Cell maturation is characterized by three distinct GFCs, including E1 (related to NK activities, cytotoxicity, and cytotoxic T-lymphocytes) dominated by Prf1, Ctla2a, Gzma, and Gzmb, M1 (related to melanoma metastasis and cytolytic function) dominated by Itgam, S1pr5, and S1pr1, and M7 (related to cell differentiation) dominated by Kcnj8 and Ly6c2.