MMP9 and columnar cell hyperplasia of the breast: Additionally, we found a decrease in pro-MMP-9 levels at the 15-day and 30-day timepoints in the cortex, but no changes in expression of pro-MMP-9 at the hippocampus and cerebellum, although pro-MMP-9 levels were downregulated in the hippocampus in IF BCAS animals at the 30-day timepoint (Fig. 5A-F) suggesting that the MMP-9 pathway is not induced during CCH-associated injury.