TGFB1 and cancer: This unstable equilibrium can be unbalanced in VSCC by different mechanisms of immune evasion and inactivation of the T cell response, such as the high expression of IDO [55], the secretion of transforming growth factor- β (TGF-β) [62] and PD-L1 [46] by cancer cells (Figure 1D) and tumor infiltration by M2 macrophages and T regs [45].