Fig. 4

TGF-β1, Smad3, and p16^INK4a expression is increased in the colonic organoids and epithelium from old mice. a TGF-β1, Smad3, and p16^INK4a expression in the colonic epithelial organoids from young and old mice (left) and sum of immunohistochemistry (IHC) score (right) (3 organoids per mouse; 3 mice per group) (Scale bar = 100 μm). b TGF-β1, Smad3, and p16^INK4a expression in the colonic epithelium from young and old mice (left) and sum of IHC score (right) (3 mice per group, scale bar = 50 μm). c Schematic illustration of how aging impacts cell cycle arrest through TGF-β-Smad3 signaling in colonic epithelial cells. ^*p < 0.05, ^**p < 0.01, ^***p < 0.001, ^****p < 0.0001 by the Mann–Whitney t-test. TGF-β, transforming growth factor β; IHC, immunohistochemistry