“CD3 and CD28 costimulation induced a complex response including decreased threonine phosphorylation in the ERK1 and ERK2 activation loops and increased phosphorylation of selected tyrosine sites on ERK1/2, p38, phospholipase C-γ, Src homology 2 domain-containing transforming protein 1, Grap2, and Vav-1, potentiating T cell activation.”