PDCD1LG2 and cancer: The basal expression of selected cell surface markers (M1, M2, inhibitory) on either human monocytes or cancer cell lines suggest that human monocytes do not express PDL2 (M2/inhibitory), VCAM-1 (M1), CD206 (M2), and have a low expression of PDL1 (M1/inhibitory) and CD163 (M2) (Fig 3A, black lines).