EXPERIMENTAL MOUSE SHARED RESOURCE: ABSTRACT The goal of the Experimental Mouse Shared Resource (EMSR) is to enhance the productivity and capabilities of University of Arizona Cancer Center (UACC) Members by providing access to in vivo models, including immunocompromised and genetically engineered mouse (GEM) models. EMSR also provides comprehensive support of experimentation in rodents (mouse and rat) and offers effective and efficient services that allow UACC Members to avoid duplication of equipment and training that would occur without such a Shared Resource. Importantly, EMSR ensures the reproducibility of technical interventions and provides the rigorous quality control that is required to complete informative analyses of animal studies. The primary services offered by EMSR are organized into two functional units: (1) a GEM Production Unit, and (2) the Experimental Rodent Unit. Services are completely complementary and together generate impactful research and help secure funding for UACC Members. Additional services associated with GEM generation include the transfer of mouse strains for cryopreservation and consulting on troubleshooting for genotyping and breeding strategies. Services offered for rodent experimentation include the inoculation of various xenograft and orthotopic tumor models and the expertise to perform services ranging from routine injections to technically challenging surgical procedures. EMSR performs all aspects of experimentation from developing genetic models of cancer, injecting tumor cells, treating and measuring tumors for drug testing, and processing tissues for experimental endpoints, including gross pathologic examinations with cryopreservation of organs/tissues and preparation of tissue for examination by UACC Members and other Shared Resources. In CY20, EMSR provided services to 101 unique users. Of these, 56 (55%) were UACC Members and 45 (45%) were non-Members, including eight (8%) external users. UACC Member usage included 30 users (54%) from the Cancer Biology Program, 19 users (34%) from Clinical & Translational Oncology, and 7 (12%) users from the Cancer Prevention & Control Program. EMSR contributed to 53 peer-reviewed publications and provided support to 222 grant applications over this period. EMSR is in compliance with the University’s Biosafety Committee rules and the Rodent Experimentation is good laboratory practice qualified.