Localization of α 1S subunit. Whole skeletal muscle fibres enzymatically isolated from Ctrl (A-D) or ΔDHPR (E-H) FDB muscles 6 months post injection were processed for immuno‐fluorescent labelling for α1 S subunit (red) and laminin (green). Scale bars, 10 μm; Arrows indicate α1 S subunit expression on sarcolemma; antibody labelling was visualized by serial confocal microscopy and represented as movies of the optical sections (Supplementary Movies S5A and S5B). (D, H) Present projections of confocal Z‐series (step between each frame is 1 μm) along XZ and YZ planes as indicated. 