Fig. 8. Replacement of the MHC-A and MHC-B PKC phosphorylation sites with alanine residues prevented their phosphorylation by the EGF-activated MHC-A and MHC-B kinase(s). Specific activity of MHC-A and MHC-B kinases, as determined by lysing TSU-pr1 cells treated with EGF and subjecting them to MHCK assay using MHC-A, MHC-B, MHC-A S/A and MHC-B T/A tail domains as described in Materials and Methods. Error bars, ±s.e.m.; n=3.