Increased ERK1/2 activity in skeletal muscle of LmnaH222P/H222Pmice. (A) Immunoblots showing phosphorylated ERK1/2 (p-ERK1/2) and total ERK1/2 in protein extracts from quadriceps, diaphragm, and tibialis anterior muscles of 20-week-old male wild-type (Lmna WT) and LmnaH222P/H222P (Lmna H222P) mice. Each lane contains protein extracts from a different mouse. The bar graph shows means ± SEM values of pERK1/2 normalized to total ERK1/2 from scanned band densities of five immunoblots from n = 5 different mice per group. **P <0.005, ***P <0.0005. (B) Differential expression of 11 selected genes in the ERK1/2 signaling pathway analyzed using real-time quantitative RT-PCR in quadriceps, diaphragm, and tibialis anterior muscles of 20-week-old male wild-type and LmnaH222P/H222P mice. White bars show relative RNA expression levels in skeletal muscles from wild-type mice Lmna+/+ mice and black bars in skeletal muscles from LmnaH222P/H222P mice. Values are means ± SEM for n = 5 mice per group; the real-time quantitative RT-PCR was performed in triplicate on each different RNA sample. *P <0.05, **P <0.005, ***P <0.0005, n.s. not significant.