Fig. 6. Processing of SREBP-1c by glucose depends on the phosphorylation of STAT3. Contracting myotubes were cultured for 48 hours in 5 mM glucose without serum. (A) Cytoplasmic and nuclear extracts were prepared at 0 minutes, 15 minutes, 30 minutes, 60 minutes and 180 minutes after the addition of 25 mM glucose (G25). The western blots were probed using antibodies against SREBP-1c precursor (p) and mature (m) forms, Tyr⁷⁰⁵-phosphorylated STAT3, Tyr⁷⁰¹-phosphorylated STAT1 or phosphorylated Erk1/Erk2 proteins. (B) Contracting myotubes were incubated in 5 mM (G5) or 25 mM (G25) glucose for 30 minutes in the absence or presence of AG490 (a specific inhibitor of Jak2 phosphorylation) or PD98059 (an inhibitor of MAPK phosphorylation). Cytoplasmic and nuclear extracts were prepared, analysed by SDS-PAGE and immunoblotted using antibodies against SREBP-1c and phosphorylated-STAT3. Western blots are representative of three separate experiments.