Figure 1. (A) The SAC silencing network SSN. Ipl1, PP1, Dam1, and Sgo1 constitute the SSN in budding yeast, which senses the tension at kinetochores and coordinates chromosome bipolar attachment and anaphase onset. (B) The working model for tension-induced SAC silencing. Chromosome bipolar attachment alters the balance of kinase/phosphatase at the kinetochore and triggers the dephosphorylation of Dam1, which induces the dephosphorylation of SAC proteins Mad1 and Bub1 to silence the SAC.