DESCRIPTION: (Applicant's Description) The Gene Knockout/Transgenic Animal Shared Resource will provide cancer researchers at the Mount Sinai School of Medicine with access to state-of-the-art technology for producing animal models for in vivo studies. The Shared Resource will provide four essential services for cancer research. The first two, production of transgenic or gene knockout mice, will allow researchers to prepare novel mouse lines that can be used to study the effects of various gene products in cancer biology. The third service, cryopreservation of mouse lines, will make it possible for researchers to create a repository of important mouse lines without the necessity to breed these lines indefinitely. The final service, rederivation of mouse lines, will allow cancer researchers at Mount Sinai to obtain mouse lines from investigators at other institutions which can ultimately be used within the rodent specific pathogen-free barrier facility at Mount Sinai. This is an important capability, since animals at other institutions which may be infected with various mouse pathogens can not be directly introduced into the barrier facility at Mount Sinai. The availability of these services through the Shared Resource will enhance the types of research projects that can be performed by cancer researchers at Mount Sinai.