The approach used for the isolation and molecular characterization of melanoma CTCs (CMCs) combines an immunomagnetic enrichment procedure with a negative selection for the common leukocyte antigen CD45, followed by positive selection targeting the CD146 antigen (expressed in more than 80% of metastatic melanomas) and ABCB5 melanocyte stem antigen [75,131,132]. The gene discussed is PTPRC; the disease is metastatic melanoma.