PMEL and melanoma: Tumour-associated or lineage-differentiation antigens are self-proteins expressed in a tightly lineage-restricted pattern and conserved in cancers of that tissue of origin—one well-characterized suite being the melanoma differentiation antigens (MDA) involved in melanosome biogenesis: MART-1/Melan-A, Tyrosinase, gp100/pmel and Tyrosinase-relaed-protein-1 and -2 [2,3,4].