- Breast tumors that overexpress nuclear metastasis-associated 1 (MTA1) protein have high recurrence risks but enhanced responses to systemic therapies. Martin, M.D., Hilsenbeck, S.G., Mohsin, S.K., Hopp, T.A., Clark, G.M., Osborne, C.K., Allred, D.C., O'connell, P. Breast Cancer Res. Treat. (2006)