William Osler Health System 1 article published in JoVE Cancer Research Differentiation of Mouse Breast Epithelial HC11 and EpH4 Cells Mulu Geletu*1,2, Victoria Hoskin*1, Blerta Starova*1,3, Maximilian Niit1,4, Hanad Adan1, Bruce Elliott1, Patrick Gunning2, Leda Raptis1 1 We describe techniques for differentiation induction of two breast epithelial lines, HC11 and EpH4. While both require fetal calf serum, insulin, and prolactin to produce milk proteins, EpH4 cells can fully differentiate into mammospheres in three-dimensional culture. These complementary models are useful for signal transduction studies of differentiation and neoplasia.