Western blotting was performed as previously described 56 (link), 61 (link). Briefly, cell lysates containing 50–100 μg of protein were resolved by electrophoresis on 10% SDS-polyacrylamide gels. Proteins were transferred to Hybond-P membranes, which were incubated in 5% non-fat dry milk for 1 hour and overnight at 4°C in 0.25% non-fat milk containing antibodies. The membranes were incubated for 1 hour at room temperature in 0.25% non-fat milk with an anti-rabbit or mouse IgG HRP-linked secondary antibody (Cell Signaling, Danvers, MA, USA). To ensure equal loading of proteins, the membranes were stripped under the same conditions as described above. They were then incubated with enhanced chemiluminescence reagents and exposed to X-ray film for 1–5 min.