Isoelectric Focusing (IEF) 6. Drain off excess mineral oil and transfer to the sample tray of Multiphor II apparatus with the gel facing upwards. 7. For each IPG DryStrip, cut two electrode wicks 2 cm in length. Soak electrode wicks with 100 µL HPLC grade water and blot with a clean wipe to ensure that the wicks are damp but not excessively wet. Place damp wicks on either end of the IPG strips and fix electrode bars onto the wicks at either end of the IPG strips. Pour mineral oil into the Multiphor sample tray until the strips are immersed. Prod wicks gently using tweezers to remove air bubbles and ensure good contact with the IPG gel. 8. Carry out IEF at 300 V for 2 h, a gradient increase to 3500 V over 3 h, and then maintain at 3500 V up to 70 kVh using an EPS 3500XL power supply. For all stages, set the current limit to 10 mA for 12 gels, and the power limit to 5 W. Maintain the temperature of the Multiphor at 17 °C using a recycling thermostatic water bath. ■ PAUSE POINT Strips can be snap-frozen on dry ice and then stored at –80 °C until required.