(a) SAC extinction at the kinetochore proceeds through PP1 targeting to Knl1, microtubule binding by Knl1, and, in metazoans, dynein-dependent stripping of kinetochore proteins including Mad1, Mad2, and Spindly, which binds to the RZZ complex. The substrates of PP1 at the kinetochore are not known but possible candidates include the MELT domains in Knl1 that are phosphorylated by Mps1. Together, these mechanisms lead to loss of SAC regulators from attached kinetochores but the interdependencies and molecular mechanisms of kinetochore eviction during SAC extinction remain largely unclear.