The retrograde response: When mitochondrial quality control is not enough

► The retrograde response compensates for mitochondrial dysfunction accumulating over a cell's lifetime. ► Autophagy and mitophagy provide mitochondrial quality control. ► Age-asymmetry in segregation of dysfunctional mitochondria is another quality control mechanism. ► Mitochondrial quality control constitutes a complex network of processes that requires a systems approach to understand fully.