Tumor cells in the upper chamber secrete CXCL8 (Fig 3F), which then diffuses and attracts neutrophils in the lower chamber by chemotaxis. On the other hand, tumor cells produce TGF-β (Fig 3B), which diffuses and enhances the N1 → N2 transformation of neutrophils (Fig 3C) in the lower chamber. The gene discussed is CXCL8; the disease is neoplasm.