Among the extracellular proteins secreted by the MMTV–Prune-1/Wnt1 cells, we identified some extracellular proteins linked to EMT, motility, and metastasis in BC, including vimentin (Vim; (Yamashita et al., 2013)), interferon-induced transmembrane protein 3 (Ifitm3; (Yang et al., 2013a)), and syndecan-binding protein (syntenin-1/Sdcbp (Yang et al., 2013b; Qian et al., 2013; Koo et al., 2002)) (Table 1). Here, WNT1 is linked to breast cancer.