The Cellsearch Circulating Melanoma Cell assay uses a human high-molecular-weight-melanoma-associated antigen (HMW-MAA), called Chondroitin Sulfate Proteoglycan 4 (CSPG4 or MCSP), as an identification marker in addition to CD146 (also known as MCAM (Melanoma Cell Adhesion Molecule) or MUC 18) to enrich CTCs from blood [48,49]. This evidence concerns the gene CSPG4 and melanoma.