The early markers Keratin 6 and Sca-1 were detected in many hyperplastic ducts and mammary tumors of Wnt-1 transgenic mice but were not increased in premalignant ducts or tumors in MMTV-Neu, MMTV-Hras, or MMTV-PyMT transgenic mice. The gene discussed is WNT1; the disease is breast cancer.