The aim of the present study was to set up and validate a reliable quantitative real-time polymerase chain reaction (qRT-PCR) protocol to describe the epithelial/mesenchymal gene signature of rare CD45−CD146+ABCB5+ CMCs isolated from the blood advanced stage melanoma (III–IV AJCC) patients and to evaluate their potential clinical value. This evidence concerns the gene ABCB5 and melanoma.