Additional signaling components of palmitate-induced CSF3 expression. (A, B, and C) Human myotubes were pre-treated for 30 min with the MEK1/2 inhibitor PD98059 (20 μmol/L; A), the p38 MAPK inhibitor SB203580 (5 μmol/L; B), or the JNK inhibitor SP600125 (50 μmol/L; C), respectively, prior to 24-hour treatment with palmitate (0.5 mmol/L). (D) Human myotubes were incubated for 20 h with anisomycin (25 μg/mL). (E and F) Human myotubes were pretreated for 150 min with the Src inhibitor PP2 (15 μmol/L; E) or for 30 min with the long-chain fatty acyl-CoA synthetase inhibitor triacsin C (TRC, 5 μmol/L; F), respectively, prior to 24-hour treatment with palmitate (0.5 mmol/L). (G and H) Human myotubes were pretreated for 24 h with JUN (G) or CEBPA (H) siRNA, respectively, prior to 24-hour treatment with palmitate (0.5 mmol/L). JUN, CEBPA, and CSF3 mRNA expression was quantified by RT-PCR. Data are given as means ± SEM. Two-group comparisons were performed using matched-pairs Student's t-test (N ≥ 3; *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001).