ADAMs (a disintegrin and metalloproteinase) family have been associated with the process of proteolytic "shedding" of membrane-associated proteins ectodomain and hence the rapid modulation of key cell signaling pathways in tissues microenvironment. A variety of cytokines, chemokines and growth factors which are initially produced as transmembrane proforms are activated by these sheddase activities. ADAM12 is highly expressed in rapidly growing tissues such as placenta and malignant tumors and it was found as one of the Candidate Cancer Genes in a comprehensive mutational analysis of human breast cancers. Our aim was to determine the gene expression profile of ADAM12 in breast cancers in comparison with normal breast and to correlate their level of expression with the clinical and pathological characteristics of breast cancers. Gene expression of ADAM12 spliced variants (12L and 12S) was evaluated using quantitative reverse-transcription PCR in samples obtained by laser capture microdissection from 38 patients with breast cancers and compared with adjacent healthy breast tissues. Both ADAM12L and 12S expression were significantly up-regulated in breast cancers, while in the normal breast, we found a very low expression. ADAM12L expression was significantly correlated with the histopathological types and, although not statistically significant, ADAM12 both variants were up-regulated in high-grade, highly-proliferative and HER2÷neu positive tumors. From these preliminary results, we found that ADAM12 could be an interesting marker and eventually a therapeutic target for breast cancer.