| Field | Specification |
|---|---|
| Target | |
| CAS no. | |
| Applications | |
| Molecular weight | |
| Molecular formula | C18H19FN4O2 |
| Purity | |
| SMILES | |
| Form | Solid |
| Storage | |
| Shipping | |
| Catalog no. (Mfr.) | |
| Main SKU |
Compound Overview
FMK is an irreversible inhibitor of RSK2 kinase that covalently modifies the C-terminal kinase domain of RSK. It is supplied as a white to light yellow solid (C18H19FN4O2, MW 342.37) at 99.83% purity.
Physical & Chemical Properties
| CAS Number | 821794-92-7 |
|---|---|
| Molecular Formula | C18H19FN4O2 |
| Molecular Weight | 342.37 g/mol |
| Purity | 99.83% |
| Appearance | Solid |
| Color | White to light yellow |
| SMILES | FCC(C1=C(C2=C(N=CN=C2N1CCCO)N)C3=CC=C(C=C3)C)=O |
| Target | RSK2 |
| Signaling Pathway | MAPK/ERK Pathway |
| Solubility | In Vitro: DMSO: 50 mg/mL (146.04 mM; Requires sonication; Hygroscopic DMSO has a significant impact on the solubility of product, please use newly opened DMSO) |
| Storage | 4°C, stored under nitrogen. In solvent: -80°C, 6 months; -20°C, 1 month (stored under nitrogen). |
| Shipping | Room temperature in continental US; may vary elsewhere. |
Literature Cited
Sources cited in this description and in the In Vitro & In Vivo Data tab. Peer-reviewed publications that used this product are listed under References.
Safety
For Research Use Only. Not for use in diagnostic or therapeutic procedures, and not for human or veterinary use. Handle in accordance with the Safety Data Sheet and your institution's chemical hygiene plan.
In Vitro
| Solvent | Solubility | Notes |
|---|---|---|
| DMSO | 50 mg/mL (146.04 mM) | requires sonication; use freshly opened DMSO (absorbed moisture lowers solubility) |
Aliquot the stock solution and store it at -80°C (up to 6 months) or -20°C (up to 1 month); stored under nitrogen; avoid repeated freeze-thaw cycles.
In Vivo
Choose the formulation that suits the animal model and route of administration; percentages are volume ratios of the final working solution. Start from a clear DMSO stock (see In Vitro above), add the co-solvents one at a time in the order listed, mixing after each addition, and prepare the working solution fresh on the day of dosing. If precipitation or phase separation occurs, gentle warming or sonication can help.
Protocol 1
| Composition | 10% DMSO + 40% PEG300 + 5% Tween-80 + 45% saline |
|---|---|
| Result | ≥ 2.5 mg/mL (7.30 mM); clear solution |
| How to prepare | Gives a clear solution at ≥ 2.5 mg/mL (saturation not determined). For 1 mL of working solution: add 100 μL DMSO stock (25.0 mg/mL) to 400 μL PEG300; then 50 μL Tween-80; then 450 μL saline to bring the volume to 1 mL. Saline: dissolve 0.9 g sodium chloride in ddH2O and make up to 100 mL. |
Protocol 2
| Composition | 10% DMSO + 90% Corn Oil |
|---|---|
| Result | ≥ 2.5 mg/mL (7.30 mM); clear solution |
| How to prepare | Gives a clear solution at ≥ 2.5 mg/mL (saturation not determined). Use with caution if continuous dosing will exceed two weeks. For 1 mL of working solution: add 100 μL DMSO stock (25.0 mg/mL) to 900 μL corn oil. |
Data provided by the manufacturer.
In Vitro
In ARVMs, pretreatment with 3 μM fmk reduces the increase in Ser386 phosphorylation but does not inhibit the increase in Thr577 phosphorylation[1]. FMK blocks relatively few of the protein kinases in the panel, although protein tyrosine kinases such as Src, Lck, Yes and Eph-A2, along with S6K1, are inhibited. FMK does not inhibit RSK when the N-terminal kinase domain is activated through a mechanism independent of the C-terminal domain[2]. In mammalian cells, Fmk potently inactivates RSK1 and RSK2 CTD auto-kinase activity with high specificity. The specific small-molecule RSK inhibitor fmk targets RSK2 and attenuates FGFR3-induced cytokine-independent growth in Ba/F3 cells. FMK inhibits the cytokine-independent proliferation of Ba/F3 cells conferred by FGFR3[3].
Data provided by the manufacturer. Numbered citations refer to the Literature Cited list in the product description.
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ADAM Sheddase Activity Promotes the Detachment of Small Extracellular Vesicles From the Plasma Membrane. J Extracell Vesicles 2025 Jul;14(7):e70114. PMID: 40673783
A Non-canonical PDK1-RSK Signal Diminishes Pro-caspase-8-Mediated Necroptosis Blockade. Mol Cell 2020 Oct 15;80(2):296-310.e6. PMID: 32979304
EGFR-phosphorylated GDH1 harmonizes with RSK2 to drive CREB activation and tumor metastasis in EGFR-activated lung cancer. Cell Rep 2022 Dec 13;41(11):111827. PMID: 36516759
FLT3-ITD Activates RSK1 to Enhance Proliferation and Survival of AML Cells by Activating mTORC1 and eIF4B Cooperatively with PIM or PI3K and by Inhibiting Bad and BIM. Cancers 2019 Nov 20;11(12):1827.
