The use of nonviral (plasmid DNA) gene delivery into skeletal muscle has increased significantly in recent years. The procedure is used to overexpress wild-type proteins, express mutant proteins, or knock down endogenous proteins. These manipulations can identify the role of a specific protein in muscle cell biology and physiology. The same procedure of plasmid DNA gene delivery can be used to introduce a gene promoter reporter construct. Such constructs contain a defined sequence of a gene promoter that regulates the expression of a "reporter." This reporter is easily measured and reflects the in vivo transcriptional activity of the gene promoter sequence under study. The gene promoter can be mutated at known transcription factor-binding sites, truncated to identify specific regions of the gene promoter that are required for transcription, or introduced into skeletal muscle with an expression plasmid for a protein believed to regulate the gene's transcription. Therefore, the use of such gene promoter reporters allows for an in-depth physiological assessment of the gene's transcriptional regulation.