We have previously established a reliable, highly sensitive, and specific quantitative real-time polymerase chain reaction (qRT-PCR) protocol to characterize the EMT gene profile of CD45−CD146+ABCB5+ circulating melanoma cells (CMCs), demonstrating the application of EMT hallmarks and EMT-TFs as potential biomarkers associated with primary tumor aggressiveness or response to therapy [46,47,57]. This evidence concerns the gene ABCB5 and melanoma.