PLG and neoplasm: For example, matrikines, such as endostatin a proteolytic product from type XVIII collagen, or those derived from elastin or plasminogen (angiostatin) cleavage, are anti-angiogenic and can act in a tumor-promoting or suppressing manner (O'Reilly et al., 1997; Sim et al., 1997; Da Silva et al., 2018).