PTEN and papilloma: To verify the contribution of Lgr5+ cells (with Pten loss) in papilloma and SCC, we performed IF staining of tissue sections of these tumors derived from Lgr5-Pten-/- mice and Lgr5-Pten+/+ mice for the expression of Lgr5, and we did not detect the presence of Lgr5-expressing cells (Figure S3).