FIGURE 7: Sit4p and Sch9p integrate nutrient and stress signaling from TORC1 with ceramide signals to regulate mitochondrial function and CLS in yeast. Cells lacking Isc1p present increased TORC1-Sch9p activity, ultimately leading to mitochondrial dysfunction, decreased oxidative stress resistance and shortened CLS. Apart from sensing signals from TORC1, the ceramide activated protein phosphatase Sit4p and the AGC protein kinase Sch9p also integrate ceramide signaling derived from Isc1p to regulate mitochondrial function, oxidative stress re-sistance and chronological lifespan in yeast.