Cells were cultured in 100 mm cell culture plates, and lysed in 2.0 ml cold RIPA buffer (sc-24948; Santa Cruz Biotechnology) with protease and phosphatase inhibitors (#P0044; Sigma-Aldrich). Lysates were centrifuged at 10,000×g for 10 min at 4 °C and the supernatant was collected. For each immunoprecipitation, a 0.9 ml aliquot of lysate was incubated with 0.5–1.0 μg of the indicated antibody for 1 h at 4 °C and the resulting immuno-complex was pulled down by incubating with 25 μl Protein A/G Plus-Agarose (#sc-2003, Santa Cruz Biotechnology) overnight at 4 °C with rotation. The beads were washed four times with 1.0 ml cold lysis buffer, boiled in SDS sample buffer at 95 °C for 5 min, and subjected to western blot analysis using appropriate antibodies. The uncropped images are provided in Supplementary Fig. 5.