A 6.9 kb fragment of pCAG-CATZ, containing the beta-actin promoter, loxP-flanked chloramphenicol acetyl transferase (cat) gene and the adjacent beta-galactosidase gene was purified and injected into fertilized FVB/N zygotes. 2 of 21 founders carried the transgene, and lines 2104 and 2112 were selected for further characterization. (J:67908)