Immunostaining for RyR1 and Orai1 in EDL fibers. (A and B) Representative immunofluorescence images obtained in EDL fibers from WT (A) and CASQ1-null (B) mice that were double-labeled for RyR1 (red) and Orai1 (green). (C and D) Fluorescence intensity profiles along four sarcomeres for the EDL fibers from WT (C) and CASQ1-null (D) mice shown by the dashed line in A. Scale bar, 5 µm (inset, 1 µm).