Effects of different ribosomal protein mutations on skin darkness and p53 levels. (A) Tails from nonmutant, Rps19^Dsk3/+, and Rps6^lox/+;Tg.K5Cre/+ animals. (B,D) Immunofluorescence for p53 in tail (B) and BM (D) sections from the ribosomal protein mutants. White lines (B) mark the dermal-epidermal junction; arrowheads mark p53-positive nuclei. (C,E) Quantitation of p53 immunostaining in the skin (C) and BM (E) of animals of the indicated genotype (n = 3-4 mice per group). Values are number of cells per high-power field (hpf) ± SEM (6 hpf per animal). P values are based on a 2-tailed t test, *P < .05, **P < .01; NS indicates not significant. Scale bars: 0.5 mm (A); 50μM (B,D).