There are five major steps of apoptosis: cell shrinkage, blebbing formation, chromatin condensation, cytoskeleton collapse, and nuclear envelope disintegration. In the first step, the cell undergoes shrinkage. Blebbing formation occurs in the second step. The sizes of blebs gradually increase overtime. In the third step, chromatin undergoes a change from a heterogeneous, genetically active shape to an inert, highly condensed form. The condensed chromatin is fragmented and packaged into apoptotic bodies. In step four, the cleavage of several cytoskeletal components by caspases ensures the swift and organized breakdown of the cell into apoptotic bodies. In the last step, caspase-mediated proteolysis cleaves protein substrates into fragments. The nuclear DNA is then partially degraded into nucleosomal units. The end result of apoptosis is that cells release apoptotic bodies and microvesicles.