A schematic diagram which shows that IL-19 acts in an autocrine manner. Hypoxia also induces IL-19 production. IL-19 directly promotes the proliferation and migration of breast cancer cells. In addition, IL-19 indirectly induces tumor progression including angiogenesis, tumor growth, and metastasis through MMP2, MMP9, IL-1β, IL-6, TGF-β, CXCR4, and fibronectin. The hypothesized working model of IL-19 in breast cancer.