Phospho-Histone H3 (pHH3) immunostaining (red cells, indicated by arrows) was used as an indicator of cell proliferation, and smooth muscle α-actin (SMA) expression (green cells, indicated by arrowheads) also was evaluated in oim/oim (A,B), Postn null (C,D), and Klotho null (E,F) aortic valves in parallel to corresponding controls. Insets in B, D, E, and F, show higher magnification of the pHH3 positive cell (red) in each low magnification panel indicated by an arrow. Note the absence of SMA staining in pHH3 positive cells.