Assessment of protein expression by means of 2‐D gel electrophoresis with and without mass spectrometry

I. Introduction 272 A. Dynamic Range of 2‐D PAGE 274 B. Solubilization Medium 275 C. Pre‐Fractionation 275 D. Electrophoretic Approaches 276 E. Multi‐Compartment Electrolyzer 277 F. Representative Examples 278 1. Proteomic Expression of a Model Breast Cancer Cell System 278 2. Two‐Dimensional Gel Electrophoresis of Mantle‐Cell Lymphoma 278 3. Monitoring Protein Synthesis/Expression Following Cellular Perturbation 280 4. Monitoring the Effect of Drugs on Tumor Cell Lines 281 II. Concluding Remarks 282 Acknowledgments 282 References 282 Careful examination of current literature, particularly over the last 5 years, reveals a wide range of approaches for the relative quantification of protein expression in cells, tissues, and body fluids. In view of such an observation, it is reasonable to ask whether researchers need new methods, or whether it is more productive to optimize and tune already existing ones. It is generally agreed that none of the existing methodologies on its own can give a full account of protein expression in a complex medium; this limitation, however, has not prevented the use of existing methods to provide valuable information on a wide range of proteins, where their expression has been correlated to certain pathologies and/or to pharmacological, genetic, or environmental factors. In the present work, an attempt is made to review the application of one of these methodologies, namely two‐dimensional polyacrylamide gel electrophoresis on its own or in conjunction with mass spectrometry, to assess protein expression, particularly when such expression can be correlated to certain pathologies.