1. Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, 9000 Rockville Pike, Building 50/3537, Bethesda, MD 20892, USA.
2. Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA.