[CAS NO. 1456858-58-4]  HG-9-91-01

HG-9-91-01 is a potent and selective inhibitor of SIK. HG-9-91-01 not only targets the ATP-binding site, but also a small hydrophobic pocket adjacent to this site that is created by the presence of a small amino acid residue at this gatekeeper site. HG-9-91-01 inhibits a number of protein tyrosine kinases that possess a threonine residue at the gatekeeper site, such as Src family members (Src, Lck, and Yes), BTK, and the FGF and Ephrin receptors. HG-9-91-01 potently inhibits the SIKs and, crucially, does not inhibit any other member of the AMPK-related kinase subfamily, which all possess a large hydrophobic residue (Met or Leu) at the gatekeeper site. HG-9-91-01 increases LPS-stimulated IL-10 production and greatly suppressed proinflammatory cytokine secretion, even when cells are costimulated with IFNγ to generate fully polarized classically activated (M1) macrophages.