What is Pathology - What causes apoptosis signals to cause cell death?

What is Pathology - What causes apoptosis signals to cause cell death?
​The initiator caspases, which work on execution caspases, are activated by the initial signal on the cell membrane or from the mitochondria. These subsequently act on enzymes, nucleic acids, and cytoskeletal proteins, causing the nucleus and cytoplasm to be fragmented into membrane-bound apoptotic entities. Neighboring cells or macrophages phagocytize apoptotic bodies.