Quercetin is detected in many botanical drugs and has been used to improve bleomycin (BLM)-induced PF, alter the expression levels of hydroxyproline, fibronectin, α-smooth muscle actin, Collagen I, and Collagen III, and inhibit SphK1/S1P signal transduction (Zhang et al., 2018). Here, FN1 is linked to pemphigus foliaceus.