COL18A1 and cancer: Likewise, WAT is richly vascularized with its inherent endothelial cells that communicate paracrinally with their “tissue-mate” fat cells, which can secrete similar proteins to those expressed in cancer—such as TNF-α, IL-6, and VEGF—and also antiangiogenic factors, such as endostatin, which—while balanced in healthy WAT—might indirectly or directly exacerbate this tissue hypoxia in obesity through inducing ineffective or repressed angiogenesis [124,131,132].