Mammary epithelial cells undergo cycles of proliferation, invasion, differentiation and apoptotic cell-death throughout adult life. The molecular mechanisms that regulate these complex and co-ordinated developmental programs are poorly understood. We have identified Id-1 protein, a negative regulator of basic helix-loop-helix transcription factors, as a critical regulator of these normal mammary epithelial cell phenotypes. We also found that Id-1 is an important regulator of the aggressive and invasive phenotype, as well as mediator of the effects of sex steroid hormones, in human breast cancer cells.

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				Y. Zhao, C. Johansson, T. Tran, R. Bettencourt, Y. Itahana, P.-Y. Desprez, and S. F. Konieczny Identification of a Basic Helix-Loop-Helix Transcription Factor Expressed in Mammary Gland Alveolar Cells and Required for Maintenance of the Differentiated State Mol. Endocrinol., September 1, 2006; 20(9): 2187 - 2198. [Abstract] [Full Text] [PDF]