IC50: 4, 18, and 23 nM for ALK5 autophosphorylation, TGF-β cellular assay, and ALK5 binding in HepG2 cells, respectively

ALK5 Inhibitor II is an ALK5 inhibitor.

The TGF-beta family of cytokines signal via serine/threonine kinase transmembrane type I and type II receptors. Binding TGF-beta1 to the receptor complex triggers activation of activin receptor-like kinase (ALK), initiating downstream signaling involving Smad transcription factors, mitogen-activated protein kinases, and PI3K-Akt signaling. ALK5 can phosphorylate Smad2 and Smad3, while ALK1 activates Smad1 and Smad5, triggering their translocation to the nucleus together with Smad4.

In vitro: ALK5 inhibitor II was identified as a cell permeable, selective inhibitor of the TGF-β type 1 activin like kinase receptor ALK5. ALK5 inhibitor II showed less potent activity (IC50s >16 μM) when tested against a panel of 9 related kinases, including p38 MAPK and GSK3. In addition, when cocrystallized with ALK5, ALK5 inhibitor II was found to be able to bind in the ATP site with the 1,5-naphthyridine N5 interacting with the backbone NH of His-283 [1].

In vivo: Up to now, there is no animal in vivo reported.

Clinical trial: So far, no clinical study has been conducted.

Reference:
[1] Gellibert, F. ,Wollven, J.,Fouchet, M.H., et al. Identification of 1,5-naphthyridine derivatives as a novel series of potent and selective TGF-β type I receptor inhibitors. Journal of Medicinal Chemistry 47(18), 4494-4506 (2004).