MRC1 and neoplasm: However, while CD206 is usually considered a tumor-associated macrophage (TAM) marker, it can also indicate an anti-tumor response.15,23 This was confirmed in our model system by a parallel increase in CD80 expression as pH increased.24,40 While care should be taken in interpreting these in vitro data relative to the more complex in vivo environment, it is tempting to speculate that the changes in polarity induced by elevating pH could impact resident TAMs and monocytes entering the TME by extravasation.