Figure 2.

Double-reciprocal plot of kinetic data from assays of KDR, RET, and cRAF protein kinase activity at different concentrations of sorafenib. ATP concentrations in the reaction mixture varied from 1/3 ATP K_m to 81 fold ATP K_m. Sorafenib concentrations are from 100 μmol/L to 1.6 nmol/L with 3-fold dilution and the concentration of peptides were kept constant at 2 μmol/L. V is picomoles of phosphate/60 min. Double-reciprocal plot shows the linear regression alignments are converge on Y axis, which means sorafenib is an ATP competitive compound on KDR, RET, which is consistent with reported. The IC₅₀ of RET, KDR are 0.4 nmol/L, 4 nmol/L in sequence.