Figure 5

Localization of Notch1, pSmad2/3 and active β-catenin. Sections of the tibial articular cartilage of 12-week normal Mig-6-flox (A, C, E) and Mig-6-flox;Prx1Cre conditional knockout (Mig-6-cko) knees (B, D, F) immunostained with antibodies against Notch1 (A, B); the TGFβ1-mediators phosphorylated Smad2/3 (pSmad2/3) (C, D); and the canonical Wnt mediator activated β-catenin (E, F). In normal articular cartilage, immunostaining is localized to occasional cells mainly limited to the superficial zone (arrows in A, C, E) while in Mig-6-cko articular cartilage, immunostaining is intensified and positively-stained cells are located not only in the superficial zone but also in deeper zones (arrows in B, D, F). Strong nuclear localization of active B-catenin is also observed in Mig-6-cko articular chondrocytes (arrowheads in F). Scale Bar = 50 μm (A-D); 25 μM (E, F).