Fig. 2. EGF-induced increases in MHC-A and MHC-B phosphorylation of TSU-pr1 cells. Cells were incubated in the presence of ³²P orthophosphate and stimulated with 7 ng ml^-1 EGF. Aliquots of TSU-pr1 were removed at different times before and after stimulation with EGF and subjected to immunoprecipitation as described in Materials and Methods. The immunoprecipitated MHC-A and MHC-B were analyzed on 7% SDS-PAGE gels and using a PhosphorImager (Fuji). Relative phosphorylation of MHC-A and MHC-B was determined by dividing the values obtained with the PhosphorImager by the values obtained by scanning of the Coomassie-Blue-stained gels, as described in Materials and Methods. The results are the average of three to six experiments.