Figure 4.
Inhibition of ERK activity by U0126, a specific inhibitor of MKK, inhibits GRASP55 phosphorylation. (A) MPM2 reactivity of GST-GRASP55 was determined after in vitro incubation with added ATP and mitotic cell extracts that had been pretreated with either 0.2% DMSO control or 20 μM U0126 for 30 min at 37°C. (B) 32P incorporation of transfected GRASP55-MYC recovered by immunoprecipitation from mitotic HeLa cells that were pretreated for 30 min at 37°C with either 0.2% DMSO control or 20 μM U0126 and then incubated for 4 h with [32P]H3PO4.