PTGS2 and central nervous system cancer: Thus, it has been published that the stimulation of cyclooxygenase-2/prostaglandin E2 and metalloproteinase-9 by ROS-activated ERKs is involved in the invasion/migration of U87 glioma cells elicited by TPA, and antioxidative substances such as quercetin, baicalein and myricetin, leading to the effective suppression of invasion/migration events in glioma cells [56].