A. GST control and GST-Twist1-N Proteins were incubated with MAPKs as indicated for in vitro phosphorylation assays. Immunoblotting (IB) was performed with pS68-Twist1 antibody. Coomassie blue staining of GST and GST-Twist1-N Proteins served as the loading control. SB203580, a p38 MAPK inhibitor; SP60125, a JNK inhibitor. B. 293 cells were transfected with HA-Twist1 plasmids in combination with H-RasV12 (+) plasmids or its mock vector (-). H-Ras, Twist1 and GAPDH mRNAs were measured by RT-PCR. H-Ras, pS68-Twist1 and tubulin proteins were measured by IB. C. 293 cells were transfected with H-RasV12 plasmids in combination with HA-Twist1 or HA-S68A-Twist1 plasmids. After 12 hours, cells were treated with cycloheximide as indicated. IB was performed with antibodies against HA (for Twist1), H-Ras and tubulin. Densitometric values were determined and plotted.