Low levels of H2O2 extends the life-span of yeast in a Prx-dependent manner (Goulev et al., 2017) and an endogenous amino-acid metabolite, namely N-acetyl-L-tyrosine (NAT), was recently shown to reduce tumor growth in mice via mitohormesis (Matsumura et al., 2020). The gene discussed is PRX; the disease is neoplasm.