Supplemental Figure S2.
Retinoic acid receptor γ (RARγ) agonists block fibrodysplasia ossificans progressiva (FOP)–like heterotopic ossification and skeletal muscle deterioration. A: X-ray images of hind legs of FOP-like model mice 1 month after induction of mutant activin receptor (ALK2Q207D) treated with vehicle or 4 mg/kg per gavage of RARγ agonist CD1530. Massive heterotopic ossification (HO) forms in control vehicle–treated mice but not in RARγ-treated mice. B: Transverse sections at the indicated level (yellow lines in A) in the X-ray images were stained with Masson's trichrome (MT). Skeletal muscle tissue severely distorts around HO in the vehicle-treated control mice, whereas deterioration of muscle tissues is much milder in the RARγ-treated group. Parallel sections (OC/Lami/DAPI) were stained for osteocalcin (OC; green), laminin (Lami; red), and nucleus (DAPI; blue). Scale bars: 5 mm (B, top panels); 250 μm (B, middle and bottom panels).