HIF1A and cancer: Thus, at the stage of HIF‐1α abundance in cells, EP4 receptors do not appear to be involved in cancer development because the abundance of HIF‐1α also induces VEGF‐A165 and VEGFR‐1, as shown in Figure 4B, to provide nutrients for rapidly growing cancer cells through the inductions of angiogenesis and/or cellular migration/metastasis, possibly via the activation of EP3 receptors, as we reported previously.26, 27 Thus, at the stage of HIF‐1α abundance in colorectal epithelial cells, cells appear to progress to cancerous phenotypes and EP4 receptor‐mediated homeostasis is no longer required.