TGFB1 and neoplasm: Furthermore, increased levels of TGF-β and increased expression of immune checkpoint molecules like the programmed cell death ligand 1 (PD-L1) and B 7 homolog 3 protein (B7H3) on the surface of the tumour cells, especially on HGGs, result in the inhibition of effector T cells and, subsequently, in further Treg infiltration [25].