A-C WT, ADAP−/−, or SKAP55−/− OT-I CD8+ CTLs were stimulated with OVA257-264-pulsed or unpulsed EL4 cells to detect the levels of NFATc1 expression, activation and nuclear entry by immunoblotting (A) or immunostaining (B). Alternatively, nuclear extracts from these CTLs were incubated with the N1 DNA probes containing NFAT-binding sites for an EMSA. The unlabeled competitor probe (Comp. N1) and the mutant probe that contains the same sequence except for carrying a mutated NFAT-binding site (Comp. mutN1) were included as controls (C). 