Figure 6

Expression of constitutively active p38β in mouse muscle induces C/EBPβ phosphorylation at Thr-188. Plasmids encoding constitutively active p38α or p38β were transfected into TA of the right leg of wild type or C/EBPβ^−/− mice, and the empty vector into the left leg. In 14 days TA samples were collected, weighed and lysed. Expression of the p38 isoforms was verified by western blot analysis of HA tag expression and ATF2 activation. A representative blot is shown (A). The TA lysate was subjected to western blot analysis of C/EBPβ phosphorylation at Thr-188 and FoxO1/3 activation. Representative blots and densitometry data are shown. Optical density of the bands that represent various proteins was measured. Levels of protein phosphorylation were normalized to that of total proteins. *denotes a difference (P <0.05) based on Student t test (B). TA, tibialis anterior.