MMP-1 was not differentially expressed in the mucosa, but increased in the submucosa and muscularis of stenotic CD intestine compared to controls, while MMP-3 expression was increased in all intestinal layers.30 Pro-MMP-1 was shown to be increased in both muscularis and mucosa of the fibrotic CD intestine compared to controls and inflamed intestine. This evidence concerns the gene MMP3 and Cowden disease.