(a) Tumour growth in vehicle or CCT365623-treated MMTV-PyMT mice. Data are represented as mean±s.d. from six mice per group. **P<0.01, Student's t-test. (b) H&E stained lungs from vehicle or CCT365623 treated MMTV-PyMT mice. Scale bar, 100 μm. (c) Quantification of lung metastasis in mice from a. All data are presented as mean±range, n=6 animals. **P<0.05, Mann–Whitney analysis. (d) Tumour growth in water or BAPN-treated MMTV-PyMT mice. Data are represented as mean±s.d. from seven mice per group. **P<0.01, Student's t-test. (e) H&E stained lungs from water or BAPN-treated MMTV-PyMT mice. Scale bar, 100 μm. (f) Quantification of lung metastasis in mice from d. All data are presented as mean±range, n=7 animals. **P<0.05, Mann–Whitney analysis. (g,h) Confocal photomicrographs of MATN2 (red) and EGFR (green) staining in primary and metastatic tumours from vehicle, CCT365623, water or BAPN-treated MMTV-PyMT mice. Scale bars, 20 μm. (i–l) Quantification of MATN2 and EGFR staining in primary or metastatic tumours from g and h. All data are represented as mean±s.e.m. Samples from six vehicle or CCT365623 and seven water or BAPN-treated mice were analysed. **P<0.01, Student's t-test.