As ecotopic expression of MMP1 to restore the wild-type level in Uev1-depleted cells also restored wild-type level of invasiveness, it is plausible to conclude that MMP1 is the critical downstream effector of UEV1A-induced breast cancer metastasis, although this study does not rule out the contributions of MMP9 and possibly other genes. This evidence concerns the gene MMP1 and breast cancer.