Experiments involving target-drug complex formation, data collection, and data processing were done using the standard operating protocol as validated previously6 (link) for the determination of atomic resolution ligand–kinase crystal structures. Protein purification6 (link) was done using a combination of affinity-based adsorption chromatography (HisTrap™; GE Healthcare), gel filtration (HiPrep 26/10 column; GE Healthcare) and ion exchange chromatography (Q Sepharose™; GE Healthcare).