Activator configuration: Transient transfection: Reporter construct (pAdCR5-LacZ) was transfected alone (P1) or was co-transfected with activator construct, pAdCMV5-cTA (Cu- and Cu+), in 293, A549, BMAdE1-78 and HeLa cells. pcDNA-SEAP was included to serve as a control for transfection efficiency. Transfections were carried out in the presence (Cu+) and absence (Cu-) of 200 μg/ml cumate. β-galactosidase activity was measured 48 h post-transfection. Reporter activity was normalized to SEAP activity in the culture medium. The figure represents data from 3 independent experiments.