Inactivation of Gadd34 ameliorates the hypomyelination in S63del mice. (A) Semithin sections stained with toluidine blue from P28 and P180 WT, S63del, and S63del/Gadd34^Δc/Δc sciatic nerves. Bar, 20 µm. (B) G-ratios in 6-mo old nerves. **, P < 0.01, relative to S63del, by Student’s t test; 8–10 microscopic fields per mouse were analyzed, from 5 mice per genotype. (C) Western blot analysis was performed on sciatic nerve lysates for the myelin proteins MAG, PMP22, and MBP. Numbers indicate relative molecular weights. One representative experiment of three is shown. (D) MBP and (E) PMP22 protein levels as measured by densitometric analysis and E. Error bars, SEM; **, P < 0.01; n = 3 repeat blots.