Rubicon (run domain Beclin-1-interacting and cysteine-rich domain-containing protein) is a protein that in humans is encoded by the RUBCN gene. Rubicon is one of the few known negative regulators of autophagy, a cellular process that degrades unnecessary or damaged cellular components. Rubicon is recruited to its sites of action through interaction with the small GTPase Rab7, and impairs the autophagosome-lysosome fusion step of autophagy through inhibition of PI3KC3-C2 (class III phosphatidylinositol 3-kinase complex 2). Negative modulation of Rubicon is associated with reduction of aging and aging-associated diseases: knockout of Rubicon increases lifespan in roundworms and female fruit flies, and in mice decreases kidney fibrosis and α-synuclein accumulation. In addition to regulation of autophagy, Rubicon has been shown to be required for LC3-associated phagocytosis (LAP) and LC3-associated endocytosis (LANDO). Rubicon has also been shown to negatively regulate the innate immune response through direct interaction with multiple downstream regulatory molecules.