Cellular distribution of dystrophin and utrophin in differentiated myotubes. Human myotubes were visualized with an A1R confocal microscope equipped with a CFI Apo TIRF 100× objective (1.49 NA) and stained as described in Materials and methods. (A–D) Quadriceps-derived myotubes. (E–H) Orbicularis oculi–derived myotubes. (I–L) EOM-derived myotubes. (A, E, and I) Brightfield images. (B, F, and J) Anti-dystrophin. (C, G, and K) Anti-utrophin and DAPI. (D, H, and L) Merged images. Bars, 10 µm.