Correlation between altered DR5 promoter activity and cellular auxin accumulation in stably transformed tobacco BY- 2 cells. Tobacco BY-2 cells stably transformed with the auxin responsive DR5rev:mRFP and the estradiol (Est) inducible XVE-PIN1-GFP or the dexamethasone (Dex) inducible GVG-PIN7 construct. (A,B) Induction of PIN1-GFP (in green) with estradiol visibly decreases DR5rev:mRFP (in red) signal intensity compared to non-induced cells as visualized by confocal imaging. (C,D) Dexamethasone-dependent induction of PIN7 visibly decreases DR5rev:mRFP signal intensity compared to non-induced cells. (E) Graph depicts mean gray values (MGV) of the DR5rev:mRFP signal intensity in PIN1 induced and non-induced cells (n = 150). (F) MGV of the DR5rev:mRFP signal intensity in PIN7 induced and non-induced cells (n = 150). (G) [3H]NAA accumulation assays in non-induced and estradiol-induced (XVE-PIN1-GFP) cells. Error bars represent standard error. Statistical significance was evaluated with the unpaired student T-test (* P < 0.05, ** P < 0.01, *** P < 0.0001).