Schwann cells in mutant nerves show abnormal differentiation. (A) Quantification of Oct6- and Krox20-positive nuclei in transverse sciatic nerve sections of P5 and P15 WT and Jab1^−/− mice (n = 5 per genotype per time point). Immunofluorescence at P5 is shown as a representative image. Bar, 50 µm. (B) Western blot for c-Jun and phosphorylated c-Jun (p c-Jun) in sciatic nerve homogenate of P15 WT and Jab1^−/− mice. Quantification is reported as the mean of three different mice per genotype and represented as a ratio of phospho c-Jun/β-tubulin and phospho c-Jun/c-Jun, assigning WT as 1. Paired Student’s t test: *, P ≤ 0.05; **, P ≤ 0.01; ***, P ≤ 0.001. Error bars indicate SEM.