Macrophages infiltrate tumors and release cytolytic factors including tumor necrosis factor α (TNF-α) to destroy the tumor (Larrick and Wright, 1990), and it was found that platelets reduced macrophage-mediated cytotoxicity in fibrosarcoma by inhibiting the effects of TNF-α (Philippe et al., 1993). The gene discussed is TNF; the disease is fibrosarcoma.