Fig. 2

Estimation of TKI affinities to NBD. The NBD dissociation constants were estimated by calibrating the kinetic model to experimental data of TKI-mediated inhibition of calcein AM efflux in cells overexpressing P-gp. Parameter fitting was performed under two assumptions: one in which calcein and TKIs simultaneously bind to the P-gp substrate site (a) and one in which calcein and TKIs compete for overlapping sites (b)