VEGFA and pituitary gland adenoma: Studies have confirmed that VEGF‐A is not only expressed in vascular endothelial cells, but also in tumor cells in pituitary adenomas (Figure 3B), while VEGF‐A/VEGF receptor (VEGFR) 1 expression was significantly upregulated in nonfunctional pituitary adenomas invading the cavernous sinus (Figure 3C), suggesting a positive role of VEGF and its receptors in the development and invasion of pituitary adenomas.59, 64