Chondroitin sulfate proteoglycan 4 (CSPG4), also known as melanoma-associated chondroitin sulfate proteoglycan (MCSP) or neuron-glia antigen-2 (NG2) in mice and rats, is a transmembrane protein, first described over 40 years ago, which is highly expressed on human melanoma cells [16]. The gene discussed is CSPG4; the disease is melanoma.