MMP9 and melanoma: Melanoma cells may express a several of matrix metalloproteinase family members (MMP‐1, MMP‐2, MMP‐7, MMP‐9, MMP‐13 and MT1‐MMP), as well as their tissue inhibitors (TIMP‐1, TIMP‐2 and TIMP‐3).47, 48 Therefore, it is possible that overexpression of EGFR led to up‐regulation of other type of MMP, what in consequence is balanced by decreased activity of MMP‐9; however, this hypothesis needs further studies.