Fig. 7. p38 MAPK promotes MyoD induction, SHPS-1 tyrosyl phosphorylation and association with SHP-2 during myogenesis. (A) Photomicrographs of C2C12 myoblasts treated either with DMSO (0.2% (v/v)) or with 30 µM SB203580 for 72 hours in differentiation medium (DM). (B) C2C12 myoblasts were induced to differentiate in the presence of DMSO as control or SB203580 (30 µM). Cell lysates were prepared from these cultures at the indicated times. These lysates were subjected to immunoblotting with (B) SHPS-1, SHP-2 or MyoD antibodies, (C) SHPS-1 immunoprecipitation followed by pTyr immunoblotting or (D) SHP-2 immunoprecipitation followed by SHPS-1 immunoblotting. The bottom panel in C shows a fraction of the same cell lysates from the above experiments immunoprecipitated with anti-SHPS-1 antibodies and immunoblotted with SHPS-1 antibodies. The bottom panel in D shows the reprobe with anti-SHP-2 antibodies.