TGFB1 and neoplasm: TAMs can also utilize a myriad of mechanisms (e.g., secretion of IDO1, TGFβ1, PGE2 and IL-10 that promote Tregs, or expression of co-inhibitory receptors as PD-L1 that lead to T cell exhaustion) that provide local protection for the tumor cells against immune recognition along the metastatic cascade (71).