CDF uptake and CDFA hydrolysis by Caco-2. (A) Net CDF fluorescence normalized to cell protein was measured following a 30 minute incubation with 5 μM CDFA in the presence of varying concentrations of MK-571 or glyceollin. Results represent the average of 2 (glyceollin) or 4 (MK-571) separate experiments, with n = 4 for each concentration per experiment. (B) CDF concentration as a function of time following incubation with 5 μM CDFA for up to 4 hours in the absence (Control, dashed line) or presence of 100 μM of either MK-571 or glyceollin. N = 3 for each condition. Specific activities based on initial rate conditions were 6.0, 6.2 and 8.5 nM/min/mg protein for control, glyceollin and MK-571, respectively.