By studying the expression of gelatinase in the brain from the sixth hour to 30th day after cerebral ischemia, Romanic, White, Arleth, Ohlstein, and Barone (1998) found that the expression of MMP‐9 increased significantly at 12 hr after ischemia, peaked at 24 hr, and lasted for several days. This evidence concerns the gene MMP9 and brain ischemia.