Palovarotene, an RAR-γ agonist, inhibits BMP signaling by accelerating the degeneration of SMAD1/5/8 proteins and blocks HO formation in FOP model mice expressing either Q207D or R206H mutant ACVR1A/ALK2 [18, 19]. The gene discussed is SMAD1; the disease is fibrodysplasia ossificans progressiva.