ADAM12, also named as MLTN and Meltrin-alpha, is involved in skeletal muscle regeneration, specifically at the onset of cell fusion. It is also involved in macrophage-derived giant cells (MGC) and osteoclast formation from mononuclear precursors. ADAM12 is expressed in human malignant tumors. It is involved in the regulation of growth factor activities and integrin functions, leading to promotion of cell growth and invasion, although the precise mechanisms of these are not clear at the present time. ADAM12's ability to degrade extracellular matrix components likely allows it to detach cancer cells from the basement membrane and assist them on their route to metastasis. But the protein's role not just as a biomarker of breast cancer but as a gateway to cancer cell migration is only now being understood.