Atomic interactions of imatinib with (a) NQO2 (Protein Data Bank (PDB) code 3FW1) and (b) ABL kinase domain (PDB 1IEP). (a) A monomer of NQO2 (green) is shown bound to its cofactor FAD (blue) and to imatinib (red). Imatinib uses stacking interactions with FAD and makes hydrophobic contacts with both subunits in the NQO2 dimer. Only residues involved in hydrophobic interactions from a single monomer are depicted. (b) The ABL kinase domain (cyan) is depicted with the DFG motif (yellow) and residues involved in direct hydrogen binding (blue) either through side chains or the peptide backbone. D381 also makes a direct hydrogen-bonding contact with imatinib (red).