Figure 1.

MAPK/ERK activation in adult Schwann cells does not affect myelin and axons stability. A, Immunoblotting of p-ERK, p-Akt, and ERK1/2 proteins in contralateral nerves 6 weeks after tamoxifen dosing in sciatic nerves of MEK1DD mutant mice (MEK) compared with controls (Ctr) mice. Data were normalized vs Calnexin. B, TEM micrographs of uninjured sciatic nerve 6 weeks post-tamoxifen dosing. C, Summary of the main parameters analyzed to study myelination and axon survival. Data are reported as percentages of myelinated and nonmyelinated axons normalized for the area in square millimeters. The g-ratio of individual fibers in relation to their axon diameter is shown in the scatter plot in D. E, Quantification of IENFD/millimeter from uninjured skin biopsy specimens. F, Internodal distance measured in teased fibers of sciatic nerve. G, Percentage of innervated NMJs in uninjured nerves. For all analyses, three to four mice per group were analyzed. Scale bar, 5 μm. *p < 0.05, two-tailed unpaired t test. Error bars indicate SEM.