B2M and melanoma: These alterations include loss-of-function mutations in the beta-2-microglobulin (B2M) gene8,9, downregulation of major histocompatibility complex (MHC)-I expression10,11, loss of MHC heterozygosity12, and silencing of melanosomal wild-type differentiation antigens (e.g., MART-1/Melan-A, gp100, TYR) during melanoma de-differentiation9,13–15.