SMAD3 and psoriasis: Our results confirm that UVB irradiation inhibits IL-17A/TNF-α-induced IL-6, IL-8, and CXCL-1 production in HDFs by decreasing the expression of IL-17RA and IL-17RC on fibroblasts through TGF-β1/Smad3 pathway, which reveals a new mechanism of the therapeutic action of UVB on psoriasis.