SMAD7 and oral lichen planus: Interestingly, TGF‐β (released from platelet alpha‐granules) is found to be an essential differentiation factor in the homeostasis as well as in the development of T regulatory (T regs), which further inhibit inflammation and autoimmunity by counteracting the effects of other T helper cells, also there was strong evidence of TGF‐β pathway blockage by increased expression of Smad‐7 in erythematous OLP (El‐Komy et al., 2015; Karatsaidis et al., 2003).