A two‐dimensional electrophoresis database of human breast epithelial cell proteins

As sequencing of the human genome progresses, attention is turning to when and where specific genes are being expressed and how that expression is regulated. The human breast, with the highly specific, but transient, function of milk production (lactation), exemplifies human gene regulation. The molecular mechanisms for the dramatic structural and functional changes involved in shifting from lactation‐capable to lactation‐incapable tissue are poorly understood, as are the mechanisms that result in deviation from normal breast cell growth into different types of breast neoplasms. We are using quantitative two‐dimensional electrophoresis (2‐DE) to determine which proteins are present in different types of human breast cells (milk‐producing and ‐nonproducing, estrogen‐receptor‐positive and ‐negative, normal and malignant) and which proteins change in abundance in response to stimuli that trigger cell differentiation, growth, or death. A composite map of proteins found in human breast cells is being generated and used as an index of human genes that are differentially expressed, both qualitatively and quantitatively. Proteins found in 15 different types of human breast cells, two from healthy tissue (from milk and reduction mammoplasty tissue) and 13 from tumor tissue, are now included in the composite map. Copies of the human breast epithelial cell protein map are available on the World Wide Web (URL: www.anl.gov/CMB/PMG/projects/index_hbreast.html) with links to quantitative data and identifications for proteins found to be differentially expressed in these epithelial cells. Links to the Swiss‐Prot and enzyme metabolic pathway databases are also provided. The World Wide Web presentation is designed to allow public access to the available 2‐DE data together with logical connections to databases providing genome‐related information.