Isoelectric
focusing (IEF) gel was carried out in glass tubes, 2.0 mm
inner diameter and 17 cm in length. The bottom of tube
was sealed with parafilm. The 4 tubes of IEF gels were
made. In brief, 1.44 g urea, 0.35 mL of acrylamide solution
[28.38% (w/v) acrylamide and 1.62% (w/v)
bisacrylamide], 0.60 mL 10% (v/v) NP-40, 0.85 mL ddH2O,
and 0.15 mL ampholine pH3.5-10:pH5-8 = 1:4) were added
together.