A form of electrophoresis in which a gel or membrane is run in one direction, rotated 90o, and run again under a different set of conditions (so as to gain a different separation of components). 2D gel electrophoresis is a powerful technique for protein separation, purification, and analysis.
        first run       
        --------->
     _________________           _________________
     | * *   *     * |           |   *           | 
     |               |           | *     *       | |
     |               |           |   *           | |
     |               |           |             * | |second
     |               |           |               | | run
     |               |           |       *       | |
     |               |           |       *       | v
     |_______________|           |_______________|

Also written '2D electrophoresis'.