These particulates also cause apoptosis and autophagy in lung epithelial cells. Polyamine analogues upregulate p53 in a cell leading to restriction of proliferation and apoptosis. YopO is a potent inducer of human macrophage apoptosis. The final result is inhibition of cell growth or stimulation of apoptosis, cell suicide. The role of p53 in betulinic acid-induced apoptosis is controversial. Strong induction of apoptosis and autophagy has also been seen. The apoptosis (cell death) of lymphocytes further worsens the immunosuppression. AP-1 controls a number of cellular processes including differentiation, proliferation, and apoptosis. This induces breaks in the DNA that ultimately lead to programmed cell death (apoptosis). Lithium possesses neuroprotective properties by preventing apoptosis and increasing cell longevity. Caspases are an important group of proteases involved in apoptosis or programmed cell death. Examples include factors responding to apoptosis and stress-induced responses. Cytochrome c is also involved in initiation of apoptosis. Apoptotic bodies are EVs that are released by dying cells undergoing apoptosis. This includes deficient phagocytic activity and scant serum components in addition to increased apoptosis.