CD44 and breast carcinoma: It is well established that MT1-MMP can increase breast cancer cell migration, invasion and metastasis through several mechanisms including dissolving the basement membrane [9], cleavage of ECM components such as laminin 5 or type IV collagen [10,11], facilitating multicellular strand formation [12], and processing of cell adhesion molecules such as CD44 [13,14] and integrin subunits [15,16].