Moreover, as SC trafficking is controlled by various factors—including phospholipid substrates such as sphingosine-1-phosphate (S1P), the growth factor chemokine stromal-derived factor 1 (SDF-1) and complement cascade (CC) cleavage fragments (e.g., C3a, C5a or C5b-C9; also known as the membrane attack complex) [29]—it is also important to analyze the role of these factors in the etiopathogenesis of schizophrenia. The gene discussed is C5; the disease is schizophrenia.