The alteration of signal pathways in MDD included activation of the negative regulation of the immune effector process, the regulation of the intrinsic apoptotic signaling pathway by p53 class mediator, response to tumor cell, and the positive regulation of chemokine production pathways, as well as the inhibited positive regulation of axonogenesis, the calcium-ion-regulated exocytosis of a neurotransmitter, and the long-term synaptic depression pathways (Figure 4I). The gene discussed is TP53; the disease is neoplasm.