Activin receptor-like kinases 1-7 (ALK1-7) regulate a complex network of SMAD-independent as well as SMAD-dependent signaling pathways. One of the widely used inhibitors for functional investigations of these processes, in particular for bone morphogenetic protein (BMP) signaling, is LDN-193189. However, LDN-193189 has insufficient kinome-wide selectivity complicating its use in cellular target validation assays. Herein, we report the identification and comprehensive characterization of two chemically distinct highly selective inhibitors of ALK1 and ALK2, M4K2234 and MU1700, along with their negative controls. We show that both MU1700 and M4K2234 efficiently block the BMP pathway via selective in cellulo inhibition of ALK1/2 kinases and exhibit favorable in vivo profiles in mice. MU1700 is highly brain penetrant and shows remarkably high accumulation in the brain. These high-quality orthogonal chemical probes offer the selectivity required to become widely used tools for in vitro and in vivo investigation of BMP signaling.

• MeSH
• Activin Receptors, Type I antagonists & inhibitors   metabolism   MeSH
• Activin Receptors, Type II * metabolism   antagonists & inhibitors   MeSH
• Protein Kinase Inhibitors pharmacology   chemistry   MeSH
• Bone Morphogenetic Proteins metabolism   MeSH
• Humans MeSH
• Molecular Probes chemistry   MeSH
• Mice MeSH
• Drug Discovery MeSH
• Pyrazoles chemistry   pharmacology   chemical synthesis   MeSH
• Signal Transduction drug effects   MeSH
• Structure-Activity Relationship MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Activin Receptors, Type I MeSH
• Activin Receptors, Type II * MeSH
• Protein Kinase Inhibitors MeSH
• Bone Morphogenetic Proteins MeSH
• Molecular Probes MeSH
• Pyrazoles MeSH