No differences in expression and proteolytic activity of MMP-1, -2, -3, and -9, nor in the expression of TIMP-1 and -2 were detected between inflamed fibrotic CD mucosa and inflamed non-fibrotic CD mucosa.26 In contrast, others found differences when non-inflamed fibrotic CD tissue was compared to control or inflamed CD tissue. Here, MMP1 is linked to Cowden disease.