The immobilized pH gradient (IPG) strips [broad range pH 3e10 (Invitrogen)] were equilibrated
for 1 h at RT with the lysed samples (36 mg protein) in rehydration buffer [143 ml 1 ZOOM 2D Protein Solubilizer 2 (Invitrogen), 0.7 ml 2 M DTT, 0.8 ml Carrier ampholytes pH 3e10 (Invitrogen), and 0.5 ml 0.2% bromophenol blue in EtOH].
Isoelectric focusing was performed using a stepwise program 175 V for 15 min, 1500 V for 45 min, and 2000 V for 45 min.
Samples were run on NuPAGE Novex 4e12% Bis-Tris ZOOM gels (Invitrogen) during SDS-PAGE. The strips were restrained on the gel with 0.5% agarose in Tris buffer (124 mM Tris, 960 mM glycine, 17.3 mM SDS in H2O) and resolved in 1 NuPAGE MES SDS Running buffer (Invitrogen)
200 V for 45 min, with 0.5 ml NuPAGE Antioxidant (Invitrogen) in the upper chamber.
Mark12 unstained standard (Invitrogen) was used as the molecular weight standard