Cells were resuspended in PBS, lysed by addition of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) sample buffer, and sonicated. Proteins were separated by 10% SDS-PAGE and transferred to nitrocellulose. After blocking in 3% skim milk, membranes were probed with a 1:100 dilution of mouse anti-Ezh2 mAb (M18EZH2, kindly provided by Prof Dr A. P. Otte, Swammerdam Institute for Life Science, University of Amsterdam, The Netherlands^37,38), washed, and incubated with anti-mouse horseradish peroxidase-conjugated secondary antibody (Amersham Biosciences, Buckinghamshire, United Kingdom). Membranes were developed using enhanced chemiluminescence (ECL) reagents (Amersham Biosciences). Equal loading of membranes was verified with rabbit anti-γ-tubulin (Sigma).