MMP9 and skin basal cell carcinoma: Depending on the phenotypic characterization of TAMs by flow cytometry, it has been reported that SCC have a higher TAM density than BCC and that these infiltrating macrophages express higher levels of arginase-1 and MMP-9 (both typically M2 markers) as well as CD40 and CD127 (considered M1 markers), in SCC compared to BCC.