PAX3 and melanoma: However, melanoma cells express unique antigens including paired box 3 (PAX3), melanoma-associated antigen recognized by T cells 1 (MART-1/Melan-A), melanoma-associated antigen 3 (MAGE-A3), and polypeptide N-acetylgalactosaminyltransferase (GalNAc-T) that are not expressed by leukocytes circulating in peripheral blood and could therefore be used to detect CTCs directly by quantitative reverse transcription PCR (qRT-PCR) without having to perform CTC isolation or enrichment procedures (Huang and Hoon, 2016).