IL17A and oral lichen planus: Given the important roles of IL-17 in OLP and the relationship between RAS and IL-17, in this study, we explored renin as well as IL-17 in the context of OLP and found that the overexpression of renin enhances IL-17 production by phosphorylating signal transducer of activated transcription 4 (STAT4) in oral keratinocytes of OLP.