CD163 and neoplasm: M0 (iNOS−CD163−), M1 (iNOS+CD163−), M2 (iNOS−CD163+), and M3 (iNOS+CD163+) TAMs could be identified in primary colorectal tumors as illustrated in Figure 4A. Although the majority of TAMs were identified in the stromal compartment, TAMs were also observed to infiltrate the tumor epithelium compartment of some tumors.