Figure 1  AP-1 activation following long-term exposure of Jurkat T-cells to PMA. Jurkat T-cells were transfected with luciferase reporter plasmids containing the AP-1 cis-elements. (A) Time-dependent AP-1 activation in response to PMA. (B) HK E. coli does not activate AP-1. (C) Dose-dependent activation of AP-1 were performed using PMA alone (grey bars) and in combination with calcium ionophore (CaI 955 μM, black bars). (D) TCR-/- deficient cells responded to PMA (162 nM) by up-regulating AP-1 activity. Statistical significance from the control was determined using Student's t-test. (n = 4). Controls were arbitrarily set to 1.