Model Description: The c-Myc gene (also known as Myc) is abnormally expressed in many tumors and plays a critical role in the regulation of cell proliferation, growth and metabolism, gene instability, stimulation of angiogenesis, malignant transformation, cell differentiation and apoptosis. These mice harbor a loxP-flanked STOP cassette preventing transcription of a CAG promoter-driven Myc oncogene. The targeted mutation was inserted into the Hipp11(H11) locus by homologous recombination. Myc is expressed when bred to mice that express Cre recombinase.