In general, antigen-presenting cell-derived or neutrophil-derived IL-23 [126] is known to be crucially involved in the differentiation, maintenance, survival, and IL-23-responsiveness of Th17 cells [76,127,128] and thereby contributes to increased levels of IL-17A in the tumor microenvironment [76], favoring an immunosuppressive and tumor-promoting milieu. The gene discussed is IL17A; the disease is neoplasm.