A proximal element regulates myf5 expression in the presomitic mesoderm. Green fluorescent protein (GFP) fluorescence is detected in the presomitic and somitic mesoderm of transgenic embryos harboring (A) -80 kb, Tg(myf5(80K):GFP) or (B) -10 kb, Tg(myf5(10K):GFP). Tg(myf5(10K):GFP) embryos also express GFP in the notochord. Dorsal views, rostral to the left. Scale bars: 200 μm.