ARG1 and neoplasm: Spatially resolved immunofluorescence and image analysis have demonstrated that hypoxia and lactate gradients within tumors generate distinct tumor-associated macrophage (TAM) phenotypes: ARG1+ macrophages preferentially accumulate in hypoxic, lactate-rich regions, whereas MRC1+ macrophages are enriched near blood vessels in normoxic areas (r = 0.6 and −0.2 correlation coefficients, respectively; p < 10) [116].