The degradation of extracellular matrix by membrane-type 1 matrix metalloproteinase (MT1-MMP) clears the way for invasive cancer cells, allowing them to migrate. But, Kajita et al. page 893, propose that MT1-MMP has another function in getting cells moving: it may cleave anchoring proteins that would otherwise hold the cell in place.
Kajita et al. look in particular at CD44, an abundant cell–cell and cell–matrix adhesion molecule. CD44 promotes migration, presumably via binding to extracellular molecules such as hyaluronic acid (HA), which activates intracellular signaling. But CD44 binding to HA might also be expected to physically retard the cell.
This is apparently where MT1-MMP comes in. Kajita et al. find that cotransfection of CD44 and MT1-MMP stimulates motility. The motility of these transfected cells and of a pancreatic tumor cell line is inhibited by both MMP inhibitors and a...
