SGC-GAK-1 (2226517-76-4) is a highly potent and selective inhibitor of cyclin G associated kinase (GAK), a member of the numb-associated kinase (NAK) family involved in membrane trafficking and sorting of proteins and is required for the maintenance of centrosome maturation and progression though mitosis. KD?= 1.9 nM with >50-fold selectivity against a panel of 400 kinases. It also displayed affinity for RIPK2 (KD?= 110 nM) and ADCK3 (KD?= 190 nM). SGC-GAK-1 displayed potent cellular activity in HEK293T cells (IC50?= 120 nM) and showed strong growth inhibition in the prostate cancer cell lines LNCaP (IC50?= 0.65 μM) and 22Rv1 (IC50?= 0.17 μM).