In the process of apoptosis, activation of executioner caspases results in cleavage of hundreds of proteins, thereby dismantling the cell. While physiological apoptosis promotes normal development and homeostasis, inappropriate apoptosis causes tissue damage, degenerative diseases, and immune system dysfunction 1. Apoptosis is an important form of programmed cell death executed by proteolytic enzymes called caspases. Precise control of cell death and survival is critical for tissue homeostasis. Thus, survival following executioner caspase activation is a normal tissue repair mechanism usurped to promote oncogene-driven overgrowth. We also show that cells expressing activated oncogenes experience apoptotic caspase activation, and that Akt1 and dCIZ1 are required for their survival and overgrowth. Through RNAi screening, we identify akt1 and a previously uncharacterized Drosophila gene CG8108, which is homologous to the human gene CIZ1, as essential for survival from the executioner caspase activation. Here, we show that, following severe tissue injury, Drosophila wing disc cells that survive executioner caspase activation contribute to tissue regeneration. However, emerging evidence suggests that some cells can survive caspase activation following exposure to apoptosis-inducing stresses, raising questions as to the physiological significance and underlying molecular mechanisms of this unexpected phenomenon. During apoptosis, executioner caspase enzyme activation has been considered a point of no return. Apoptosis is an ancient and evolutionarily conserved cell suicide program.
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