MAPK3 and Osteochondroma: Thus, Acvr1(R206H)Fl;Cre-ERT2 mice resemble multiple clinical FOP features found in human FOP patients, including progressive HO, an orthotopic fusion of cervical vertebrae, a fusion of thoracic and lumbar vertebrae, osteochondromas, and early onset degenerative joint disease53, which were all substantially prevented by the treatment with amiR-RH6.ACVR1opt (Fig. 6i).