Cultured DRG neurons from RGMb-deficient mice have decreased BMP-2-mediated signaling. DRG neurons from RGMb-deficient and WT LMs were cultured in varying concentrations of BMP-2 and then assayed for phospho-Smad (pSMAD) expression. A, Dissociated DRG neurons were immunostained for anti-pSmad (red) and anti-β-tubulin (green). Scale bars, 10 μm. B, Quantification of pSmad intensity. Values represent mean ± SEM. *p < 0.001, statistically significant difference from WT LM. C, Western blot demonstrating BMP-2 (100 ng/ml for 1 h) increased pSmad1/5/8 induction in cultured DRG neurons from adult WT mice. β-Tubulin was used as a loading control.