Moreover, one study reported that inhibition of Hif1a-encoded protein attenuated BBB damage in acute cerebral ischemia, and we also found that Hif1a mRNA was down-regulated by radiation treatment in the present study [42], while deficiency of Cdc42-encoded protein also displayed increased vascular permeability in vivo and activation of CDC42 might protect endothelial barrier [43,45]. The gene discussed is HIF1A; the disease is brain ischemia.