Matrix metalloproteases promote tumor cell invasion, epithelial-to-mesenchymal transitions, and metastases, but whether they directly regulate stem cells is unknown. In this issue of Cell Stem Cell, Kessenbrock et al. (2013) now show that MMP3, independent of its proteolytic activity, regulates murine mammary stem cells by sequestering noncanonical Wnt signaling ligands, which has implications for breast cancer pathogenesis.
Copyright © 2013 Elsevier Inc. All rights reserved.