Effects of MEK/ERKs and p38 pathways on myogenic transcription factors and myosin expression. RD cells were left untreated, treated with TPA, treated with SB 203580 in the absence or in the presence of TPA and treated with U0126 in the absence or in the presence of TPA for the times indicated. Pre-treatment with SB 203580 or U0126 was performed for 1 hour. Immunoblots of total lysates were performed using specific antibodies recognising myogenin, MyoD and sarcomeric myosin heavy chain (MHC). α-tubulin expression shows equal loading. The data shown are representative of two independent experiments.