Our data is at odds with the notion that high MT1-MMP expression is crucial for tumour progression, as numerous studies report that MT1-MMP overexpression is associated with enhanced migratory ability and tumourigenecity [17, 26, 27, 33, 34, 54], although there is also evidence in agreement with our study which shows that high MT1-MMP overexpression is insufficient to increase metastasis of human cancer cells [31]. This evidence concerns the gene MMP14 and cancer.