Transgenic mammary epithelial osteopontin (spp1) expression induces proliferation and alveologenesis.

Osteopontin (OPN) Spp1 is involved in differentiation of the mammary gland. We engineered mice to overexpress OPN in mammary epithelium and describe an altered mammary phenotype. Three transgenic (Tg) founder lines FVB/N Tg(MMTV-Opn)((1-3BOR)) were propagated after FVB/NJ pronuclear injections.