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J Cell Physiol. 2001 Oct;189(1):91-105.

Characterization of C/EBPbeta isoforms in normal versus neoplastic mammary epithelial cells.

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Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA.

Erratum in

  • J Cell Physiol 2002 Jan;190(1):131.


A member of the CCAAT Enhancer Binding Proteins (C/EBPs) family of transcription factors, C/EBPbeta, has recently proven to be an important player in both growth and differentiation of the epithelial cells in the mammary gland. When the gene for C/EBPbeta is disrupted in mice, these mice fail to either develop normal mammary ducts during puberty or pregnancy, or to lactate upon parturition. C/EBPbeta can be present in cells in three isoforms: C/EBPbeta-1, -2, and -3. These isoforms have the same carboxy terminus but different N-termini due to alternative translational initiation at three different initiator codons within the C/EBPbeta mRNA. Using a commercially available antibody specific to the C-terminus of C/EBPbeta and a novel antibody specific to the N-terminus of C/EBPbeta-1, we have uncovered a striking difference in the forms of C/EBPbeta present in normal mammary epithelial cells versus breast cancer cell lines. C/EBPbeta- 1 is found exclusively in normal mammary epithelial cells, whereas C/EBPbeta- 2 is found only in dividing cells, both normal and neoplastic. Our preliminary data suggest that the prevalent form of C/EBPbeta in cancer cells, C/EBPbeta- 2, can activate genes which push the cell to divide, such as cyclin D1.

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