Abstract
Angiogenesis, the formation and growth of new blood vessels from pre-existing vasculature, is essential for many physiological and pathophysiological processes such as pregnancy, embryonic development, wound healing and tumors. This process is controlled by the balance between pro- and anti-angiogenic signals. The balance can be tilted by the cancer cells, which requires new vessel formation for progression. The stimulatory angiogenic factors such as vascular endothelial growth factor (VEGF) drive vascular growth by attracting and activating cells within the microenvironment of the tumor. Scientists believe that angiogenesis may be a rate-limiting for tumor growth and metastasis. An effective therapy of cancer should involve targeting combinations of angiogenic factors as well as the tumor microenvironment.