CISD2 and steatosis: In our study, the presence of overt steatosis, macrophage infiltration, and fibrosis in aged livers was found to be remarkably attenuated in the Cisd2TG mice (Figure 1g–j), which supports the hypothesis that maintaining a persistently high level of Cisd2 throughout a lifetime indeed is able to delay aging and result in an old mouse that has a younger and healthier liver.