Model Description: A Cre-WPRE-polyA expression cassette was knocked into the Myf5 gene start codon site. Myogenic factor 5 (Myf5) belongs to the MRF family transcription factors that regulate myogenesis. It is expressed in the skeletal muscle and satellite cells. Severe loss of skeletal muscle following ablation of Myf5-expressing progenitors. This strain is useful in studying the differentiation of skeletal muscle.