TP53I3 participates in the generation of reactive oxygen species (ROS). TP53I3 has low NADPHdependent naphtoquinone reductase activity, with a preference for 1,2-naphtoquinone over 1,4-naphtoquinone. TP53I3 has low NADPH-dependent diamine reductase activity (in vitro). TP53I3 is localized to the cytoplasm and induced in primary, non-transformed and transformed cell cultures after exposure to genotoxic agents. TP53I3 microsatellite polymorphism is associated with differential susceptibility to cancer.