MRC1 and neoplasm: In humans and mice, frequency of PD-1+TAMs increases with disease stage and tumor progression, respectively.120 Expression of PD-1 by TAMs has been shown to promote tumor progression by facilitating induction of oxidative metabolism that supports pro-tumorigenic and anti-inflammatory functions.86 As such, PD-1+ TAMs expressed high levels of CD206, ARG1 and IL-10, relative to their PD-1 counterparts.