FMK

FMK is a an irreversible RSK2 kinase inhibitor, that covalently modifies the C-terminal kinase domain of RSK. In Vitro: Pretreatment of ARVMs with 3 μM fmk attenuates the increase in Ser386 phosphorylation, but it has no inhibitory effect on the increase in Thr577 phosphorylation^[1]. FMK inhibits relatively few protein kinases in the panel, although it does inhibit protein tyrosine kinases, such as Src, Lck, Yes and Eph-A2, as well as S6K1. FMK will not inhibit RSK if the N-terminal kinase domain are activated by a mechanism that is independent of the C-terminal domain^[2]. Fmk potently inactivates the CTD auto-kinase activity of RSK1 and RSK2 with high specificity in mammalian cells. Targeting RSK2 by a specific small molecule RSK inhibitor fmk attenuates FGFR3-induced cytokine-independent growth in Ba/F3 cells. FMK inhibits cytokine-independent proliferation of Ba/F3 cells conferred by FGFR3^[3].