PROJECT SUMMARY The Animal Tumor Models Shared Resource (ATM-SR) provides services in three major areas: (i) transgenic and knockout mice, (ii) preclinical oncology, and (iii) animal histopathology services. The primary goal of the ATM-SR is to facilitate high-impact cancer-relevant research done by Stanford Cancer Institute (SCI) members by providing state-of-the-art and comprehensive animal resources. The transgenic and knockout mouse production services were established at Stanford in 1996 with the overall objective of providing genetically modified mouse models and associated supporting technologies to Stanford investigators at cost- effective rates. Preclinical oncology services, including study design, tumor induction, drug administration, PK and PD study, data collection and analysis, were initiated by the SCI in 2007. These services are provided by the Transgenic, Knockout and Tumor Model Center (TKTC). The Veterinary Service Center (VSC) in the Department of Comparative Medicine manages the animal histopathology service component of the shared resource. Major services include tumor analysis by histology, immunohistochemistry and pathological interpretation. Since the last review, the animal histology laboratory underwent a major renovation and expansion. In 2020, 45% of users were SCI investigators. Members from all programs regularly use the ATM- SR, with the heaviest use coming from the Cancer Biology and Cancer Stem Cells and Cancer Therapeutics programs. The ATM-SR contributed to over 17 cancer-focused SCI member publications since 2015; 10 of them were high-impact. The annual budget of the ATM-SR is $1,250,002 yet the CCSG request is $105,312. Accordingly, the ATM-SR leverages extensive institutional support and seeks only 8% from CCSG funds. The ATM-SR is focused on three major scientific aims: (1) to produce transgenic and knockout mice, (2) to provide preclinical oncology model services, and (3) to provide histopathology services.