The cryoEM 3D structure of the complex between zosuquidar and human P-gp in the inhibitor-bound intermediate form (PDBID: 6qee) was obtained from the Protein Data Bank (PDB) . The protein was prepared using AutoDock Tools , following the standard preparation protocol : adding polar hydrogens, assigning Gasteiger-Marsili atomic charges , then merging non-polar hydrogens.