Cell-based kinetics study of the inhibition of VKOR by warfarin and fluindione. (A) Michaelis-Menten plot of VKOR activity as a function of KO concentration in the absence and presence of fluindione. FIXgla-PC/HEK293 reporter cells were cultured with increasing concentrations of KO containing 0, 0.94, 1.88, 3.75, 7.5, 15, and 30 nM fluindione for the activity assay. (B) Lineweaver-Burk plot of the experimental data of panel A. (C) Cornish-Bowden plot of the experimental data of panel A. (D) Michaelis-Menten plot of VKOR activity as a function of KO concentrations in the absence and presence of warfarin. FIXgla-PC/HEK293 reporter cells were cultured with increasing concentrations of KO containing 0, 0.62, 1.25, 2.5, 5, 10, and 20 nM warfarin for the activity assay. (E) Lineweaver-Burk plot of the experimental data of panel D. (F) Cornish-Bowden plot of the experimental data of panel D.