MMP26 and neoplasm: In addition, in subcutaneous tumors immunofluorescence stainings revealed an increasing signal intensity for MMP-2 and MMP-9 in the tumor islands (Fig. 4C and D) and an increasing number of distinct MMP-26 positive tumor cells (keratin positive, not shown) together with an increasing MMP-26 staining of tumor islands with GM-CSF overexpression (Fig. 4E).