TGFB1 and neoplasm: On the one hand, MDSCs induced by tumour progression selectively promoted the proliferation of Tregs in a TGF-β-dependent manner in vivo [56], and also promote the production of Tregs via CD73 highly expressed in MDSCs, which can produce adenosine by hydrolysis and further binds to A2aR, and augment the immunosuppressive effects [51, 57].