Figure 1. Newly-identified functions of the ESCRT protein Chmp4c at kinetochores. In prometaphase, Chmp4c promotes localisation of the RZZ and Mad1-Mad2 complexes to unattached kinetochores (arrow, A) leading to spindle assembly checkpoint (SAC) activation. Chmp4c also promotes stable kinetochore-microtubule interactions (A). In the presence of improper kinetochore-microtubule attachments (B), additional proteins (indicated by a question mark) mediate RZZ-kinetochore targeting. In metaphase (C), Chmp4c is removed from kinetochores leading to RZZ and Mad1-Mad2 stripping and SAC silencing.