MMP9 and cholesteatoma: Thus, from an universe of studies about collagenases, growth inhibitors and cholesteatoma prolipheration, osteolytic enzymes, bacterial toxins such as lipopolysaccharides and tumor necrosis alpha factor, in 1996, Schonermark, Mester, Kempf, Blaser, Tscheche and Lenarz studied cholesteatomas and metalloproteinases, which are proteolytic enzymes responsible for bone homeostasis, present in greater quantities in osteolytic inflammatory diseases and observed the presence of MMP2, MMP9 and MMP3 in the basal and suprabasal cells of cholesteatomas.