Characterization of CFTR inhibition by CFTRinh-172. (a) CFTR functional assays as in Figure 1b for indicated [CFTRinh-172]. (b) Time course of inhibition showing CFTR-mediated I– transport rates at different times after addition of 2 μM CFTRinh-172. Inset: Time course of inhibition reversal showing I– transport rates at different times after washout of 1 μM CFTRinh-172. Mean ± SE is shown from three sets of experiments. (c) Inhibition of CFTR after stimulation by different agonists, including benzoflavone and benzimidazolone UCCF compounds (14), genistein, CPT-cAMP, 8-methoxypsoralen (8-MPO), and 8-cyclopentyl-1,3-dipropylxanthine (CPX) (all 50 μM) (SE; three sets of experiments). Black bars, agonist; white bars, agonist + 5 μM CFTRinh-172.