PDCD1LG2 and neoplasm: Moreover, CAFs upregulate the production of regulatory T cells (Tregs) by secreting TGF-β in tumor microenvironments.9 Michael R. Nazareth et al.10 also found that CAFs from human non-small cell lung cancer had a suppressive effect upon tumor-associated T-cell activation and this suppressive effect could be abrogated by the blockade of B7H1 or B7DC.