Fig. 1.

SB431542 suppresses UVB-induced Smad phosphorylation in skin and skin tumor formation. (A) Immunoblot of skin tissue at indicated times post-UVB IR from skin hairless (SKH1) mice pretreated with SB43152 (SB) or acetone (V) for 1h before UVB (2.4 kJ/m²). (B) Skin tumor number per week in SKH1 mice treated with 2.4 kJ/m² UVB IR 3× per week for 25 weeks with 1h pretreatment with SB431542 (n = 13) or acetone vehicle (n = 10). Lesions ≥1mm³ in volume were counted. *Significantly different from acetone-treated group at indicated time points, P < 0.05. V = vehicle. (C) Bromodeoxyuridine-positive tumor cells per field. Tumor sections were stained with anti-bromodeoxyuridine by IHC and the number of positive cells per 40× field was determined and averaged from 6 to 10 fields per tumor, n = 17 tumors for vehicle and 10 for SB-treated tumors. (D) Tumor grade determined blindly from H&E stained sections, n = 35 and 48 tumors in control and SB-treated groups, respectively.