SMAD1 and cancer: This compound specifically inhibits BMP receptor-dependent phosphorylation of SMAD1/5/8 while mainly sparing the phosphorylation of SMAD2/3 by the activin and TGF-β receptors.49 Drug screening based on LDN-193189 specificity identified Saracatinib, an FDA-approved cancer drug, to target fibrodysplasia ossificans progressiva, a rare disease characterized by ectopic calcification of soft tissues through dysregulation of BMP/SMAD1 pathways, thus revealing a possible therapeutic strategy in patients with mild/moderate aortopathy and microcalcification.50