A list of molecular descriptors, together with the number of the resulting clusters obtained for both substrates and inhibitors, are summarized in Table . For each of the 6 clustering schemes, the most representative molecule of each cluster (i.e., the closest molecule to the cluster centroid) was selected, generating 6 representative sets for P-gp substrates and 6 representative sets for inhibitors. Next, each molecule from each set was docked into the P-gp binding site and the best docking pose of all the molecule in each set was converted into a 3D common pharmacophore model , based on the AutoDock force field/atom types.