Figure 4. Epidermal proliferation and differentiation are reduced in CRABP-IIknock-out mice. (A) Representative images of Ki67 immunostaining of young/adult and old wild-type (WT) and CRABP-II knock-out (KO) skin. Scale bar: 50µm. (B) Bar graphs show semiquantitative evaluation of Ki67 positive epidermal keratinocytes and dermal cells (n=10 young/adult and n=10 old WT, n=10 young/adult and n=10 old CRABP-II KO). Values are mean ± SEM. t-Test: *, ** and *** indicate p< 0.05, p< 0.01 and p< 0.001, respectively. (C) Representative images of cytokeratin 1 (CK1) immunostaining of young/adult and old WT and CRABP-II KO skin. Scale bar: 50µm. (D) Bar graphs showing the semiquantitative CK1 evaluation (n=10 young/adult and n=10 old WT, n=10 young/adult and n=10 old CRABP-II KO). Mann-Whitney’s U-test. Abbreviation: AU, arbitrary units.