The human STIM1 cDNA encoding the shorter spliced form was cloned into a human ACTA1 promoter (modified with a troponin 1 element to enhance expression in slow fibers) to create a skeletal muscle-specific transgenic strain. Expression is increased approximately 6-fold in the quadriceps, and at uniformly high levels in a broad range of skeletal muscle groups. No expression is observed in the heart. The transgene is integrated on the Y chromosome in this "low expressor" line.