CA9 and neoplasm: HIF-1α becomes activated in response to radiation exposure in hypoxic solid tumors and functions by protecting tumor blood vessels from the cytotoxic effects of radiation via inducing the expressions of VEGF, GLUT-1, or CA9, assuring the delivery of oxygen and nutrients to cells, and eventually accelerating tumor (Horsman et al., 2012; Towner et al., 2013).