1. Cell Signaling Technology Inc., 3 Trask Lane, Danvers, MA 01923, USA.
2. Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
3. Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA.
4. Division of Signal Transduction, Beth Israel Deaconess Medical Center, Boston, MA 02115, USA.