Due to a lack of markers and a consensus concerning the definition of these cells, several different proteins, including CD14, CD45, CD68, and/or CD163, to identify immune lineage and EPCAM and/or pancytokeratins, including CK8, CK9, and CK19, to identify epithelial lineage were used to identify and characterize these cells from circulation and in tumor biopsies [5,6,7,8,18,23,24,25,26,27,28,29,30,31,32,33,34]. Here, CD163 is linked to neoplasm.