MMP9 and cholesteatoma: Furthermore, it is known that VEGF, MMP-2, and MMP-9 affect each other to promote or inhibit angiogenesis in different tumors [61], and that the intercorrelations we found in our research between MMP-2, MMP-9, and VEGF may support the belief that similar activities are present in cholesteatoma tissue; however, this needs to be proved.