LDN 193189 inhibits the activity of the Bone Morphogenetic Protein (BMP) type I receptors ALK2 and ALK3 with IC₅₀ values of 5 nM and 30 nM respectively and shows weaker effects on activin and the TGF-β type I receptors ALK4, ALK5 and ALK7 (IC₅₀≥ 500 nM). It inhibits the activation of the BMP signaling effectors SMAD1, SMAD5 and SMAD8 in a dose-dependent manner in C2C12 cells. LDN-193189 significantly reduces tumor growth in SCID mice bearing MDA-PCa-118b tumors