Figure 3.

Loss of Smad4 resulted in a transient increased proliferation in epidermis and HFs. (A–F) Ki67 immunofluorescence on mice dorsal skin sections at 3 (A and D), 6 (B and E), and 12 mo (C and F), respectively. In Smad4 mutant epidermis there was an increase in the number of Ki67-positive keratinocytes at 3 mo (D) compared with that of wide-type mice (A), whereas it decreased gradually at 6 (E) and 12 mo (F). (G–L) Ki67 immunofluorescence of whole mount mouse tail epidermis at 3 (G and J), 6 (H and K), and 12 mo (I and L) confirmed the transient increased proliferation in Smad4 mutants. (M) Percentage of Ki67-positive cells; n = 6 for each time point and genotype. **p < 0.01. Bar, (A–F) 50 μm; (G–L) 100 μm.