Western Blot Analysis of Epithelial-Mesenchymal Transition

Protein lysates were harvested from the cells using 1× RIPA lysis buffer (Nacalai Tesque, Kyoto, Japan) and kept on ice for 30 min before being centrifuged at 10,000 g for 10 min at 4 °C to obtain the supernatant. Protein lysates (50 μg) were subjected to SDS-polyacrylamide gel electrophoresis and western blot analysis as described [19 (link)]. Dilutions and the sources of the antibodies used are as follows: E-cadherin (CDH1, 1:1000, Cell Signaling Technology), occludin (OCLN, 1:1000, Merck Millipore), vimentin (VIM, 1:1000, Cell Signaling), SNAI1 (1:250, Cell Signaling) and GAPDH (1:2000, Cell Signaling). The protein bands were detected using a horseradish peroxidase-conjugated secondary antibody (1: 10,000, Abcam, Cambridge, UK) for 1 h at room temperature and visualized with the Amersham ECL Western blotting substrate (GE Healthcare), according to the manufacturer’s protocol. The mean of multiple blots is presented (Fig. 4b); the error bars represent standard errors of the mean, SEM.