A 12% separating gel and a 4% stacking gel were prepared for SDS–PAGE, followed by Coomassie Brilliant Blue R-250 staining. The gels were captured by an image analyzer (E-Box VX2 coupled with E-Capt software, Heidelberg, Germany) for protein bands quantitation. For two-dimensional electrophoresis, the desalted protein samples were resuspended in a lysis buffer at 350 lL (100 lg of protein) and applied onto IPG strips (18 cm, pH 4–7 Nonlinear IPG strip) (GE Healthcare Life Sciences, Pittsburgh, PA). After rehydration, isoelectric focusing was conducted at 10,000 V for 60,000 V h. The equilibrated strips were then transferred onto a 10% SDS polyacrylamide slab gel (18 cm 18 cm), and the separated proteins were then visualised using the Typhoon 9200 laser scanner, and image data were analysed using ImageMaster 2D Platinum 7.0 Software Package .