Comparison of cTA and rcTA activity and expression: A. 293-CR5-LacZ cells were transfected with pAdCMV5-cTA or pAdCMV5-rcTA in the absence or presence of 200 μg/ml cumate. Forty-eight hours later the cells were stained for β-gal activity. B. 293-CR5-LacZ cells were co-transfected with pcDNA-SEAP and pAdCMV5cTA or pAdCMV5-rcTA in the presence or absence 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.