The Transgenic Animal/ES Cell Resource Shared Facility is an essential component of the UAB Comprehensive Cancer Center. With completion of the human and mouse genome sequences, genetically modified mouse models are more essential than ever in elucidating disease mechanisms and developing approaches to therapies for cancer. This shared facility provides unique services for the development of genetically modified mouse models and has a long track record of outstanding service. The specific aims include: 1. Provide efficient, cost effective production of transgenic mouse models for Comprehensive Cancer Center investigators by microinjection of gene constructs into fertilized mouse eggs or ES cells into blastocysts; 2. Provide additional services such as cryopreservation of embryos, embryo rederivation to produce pathogen-free mice, and assisted reproduction techniques (e.g., in vitro fertilization [IVF], superovulation, and embryo transfer); 3. Provide expert consultation services to help investigators design the most effective transgene constructs strategies for molecular diagnosis of transgenic mice, and breeding strategies required for perpetuation of transgenic mouse lines. The services provided are not available through any other mechanism except costly commercial alternatives that do not supply the complete set of services provided by this facility.