Meanwhile, development of resistance to radiotherapy due to expression of transforming growth factor-β1 (TGF-β1) is implicated as an endogenous factor, particularly when secreted in an EV-associated form (TGF-β1EV) within radiated tumours which eventually enhanced infiltration of Tregs and phosphorylation of protein kinase C zeta (PKC-ζ) in breast tumour tissue [124]. This evidence concerns the gene TGFB1 and neoplasm.