BACKGROUND & AIMS: Mitochondrial dysfunction has been implicated in aging and various cancer development. As highly dynamic organelles, mitochondria constantly undergo fission, mediated by dynamin-related protein 1 (DRP1, gene name RESULTS: L- CONCLUSIONS: Mitochondrial dynamics and stability are essential for maintaining hepatic mitochondrial homeostasis and hepatocyte functions. Loss of hepatic DRP1 promotes liver tumorigenesis by increasing pyrimidine metabolism and activating the cGAS-STING-mediated innate immune response.