This star-shaped protein complex is called an apoptosome, and it is constructed in cells to bring about cell death. It’s actually part of a cell’s self-destruct system. When a cell becomes stressed or old, and ceases to function properly, a series of signals bring about apoptosis, or programmed cell death. This is a good thing, and part of the natural life cycle of a cell. Unfortunately, this process can be blocked in cancer cells, preventing your immune system from killing them off.
In this image (derived mostly from pdb 3j2t) , cytochrome C (the blue guys) have bound to Apaf-1 (the orange guys), prompting them to form apoptosomes. The apoptosomes will then begin a cascade of Caspase activations which will end in the destruction of the cell’s organelles, and ultimately the cell itself.