STK16-IN-1 is a cell-permeable pyrrolonaphthyridinone compound th at acts as an ATP-competitive inhibitor against NAK (Numb Associated Kinase) family serine/threonine kinase STK16 (IC50/substrate = 0.91 μM/4EBP1 and 1.2 μM/DRG1, [ATP] = 20 μM) with excellent selectivity over a panel of 378 kinases. Despite its inhibitory potency against PI 3-Ks (IC50 = 1.07, 0.856, 0.867 μM against p110α/p85α, p110δ/p85α, p110γ , respectively) in cell-free assays, STK16-IN-1 is ineffective against their cellular activity up to 10 μM concentration. STK16-IN-1 treatment (10 μM for 72 hrs) is shown to cause cell number reduction (~50% in HCT-116 and MCF-7 cultures), as well as increased populations of binucleated cells (~5-fold in MCF-7 culture) and G2/M cells (~7 and 3-fold in HCT-116 and MCF-7 cultures, respectively) in an STK16-dependent manner. A useful tool for elucidating STK16 biological functions.
