CD274 and neoplasm: Lactate has also been shown to induce upregulation of PD1 on Tregs (12) and of PD-L1 on tumor-associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs) (13, 14), and also to skew M2 polarization of macrophages (15, 16), thereby further contributing to immunosuppression in the TME.