Immunohistochemical staining for Pten. Sections of mammary glands (A, D) and tumors (B, C, E, F) were stained for Pten (A, B, D, E, F) or control rabbit Ig (C) and counterstained with hematoxylin. Genotypes of mice were Pten+/+ (A); Wnt-1 TG, Pten+/+ (B); and Wnt-1 TG, Pten+/- (C-F). (E) and (C, F) were from tumors with or without LOH, respectively. A 40x objective was used.