Visualization of osimertinib, a third-generation EGF receptor kinase inhibitor, bound within the nucleotide binding site of the EGF receptor kinase domain [PDB:6JXO], covalently attached through side chain of cysteine 797. Covalent linkage helps maintain the inhibitor in the correct poition, overcoming preference for ATP as natural ligand. Selective preference for the natural ligand ATP is characteristic of EGF receptors bearing threonine>methionine mutation (T790M) at the gatekeeper residue position, accounting for reduced efficacy of first generation kinase inhibitors which are not covalently linked. Visualization via Mol* viewer (Sehnal et al. Nucleic Acids Research, 2021; https://doi.org/10.1093/nar/gkab314.)