MMSET is expressed ubiquitously in early development and its deletion is associated with the malformation syndrome called Wolf-Hirschhorn syndrome. It is involved in the t(4;14) (p16;q32) chromosomal translocation, which is the second most common translocation in multiple myeloma (MM) and is associated with the worst prognosis. MMSET expression has been shown to promote cellular adhesion, clonogenic growth and tumorigenicity in multiple myeloma. MMSET expression has been recently shown to increase with ascending tumor proliferation activity in glioblastoma multiforme. These data demonstrate that MMSET could be implicated in tumor emergence and/or progression. Therefore, we compared the expression of MMSET in 40 human tumor types--brain, epithelial, lymphoid--to that of their normal tissue counterparts using publicly available gene expression data, including the Oncomine Cancer Microarray database. We found significant overexpression of MMSET in 15 cancers compared to their normal counterparts. Furthermore MMSET is associated with tumor aggressiveness or prognosis in many types of these aforementioned cancers. Taken together, these data suggest that MMSET potentially acts as a pathogenic agent in many cancers. The identification of the targets of MMSET and their role in cell growth and survival will be key to understand how MMSET is associated with tumor development.