Figure 1.

Structures of the multitargeted tyrosine kinase inhibitor sunitinib (A) and the ULS-linkable sunitinib derivative 17864 (B). The aliphatic N-2-(diethylamino) ethylene sidechain of sunitinib has been replaced by a N-4-methylpyridine side chain (red). When binding to target kinases, the oxindole moiety (blue) of the drug is located in the adenine region of the ATP-binding pocket, while the N-2-(diethylamino) ethylene moiety or N-4-methylpyridine are protruding outwards.

Abbreviation: ATP, adenosine triphosphate.