CSPG4 and melanoma: The chondroitin sulfate proteoglycan 4 [CSPG4; also known as melanoma-associated chondroitin sulfate proteoglycan (MCSP) or neuron-glial antigen 2 (NG2)] was recognized as an important factor in the aggressiveness of melanoma decades ago, but successful intervention focused on CSPG4 has remained elusive [3–5].