Ubiquitin in the regulation of protein dynamics and localization in mitosis. Proteolytic and nonproteolytic mechanisms are depicted with light orange and light blue background, respectively. (A) Upon mitotic entry, chromosomes condense and the cell assembles a bipolar mitotic spindle. The kinases Aurora B (AurB) and PLK1 both contribute to the establishment of correct, bioriented, kinetochore–microtubule attachments by destabilizing incorrect attachments and stabilizing correct ones, respectively. (B) Transit to anaphase occurs when the APC/C is no longer inhibited by the MCC and is activated by CDC20. MCC disassembly is promoted by autoubiquitylation of CDC20 within the APC/C-bound MCC and by the ubiquitin reader CUEDC2. The irreversibility of this transition necessitates cyclin B destruction, as otherwise the SAC is reactivated (Clijsters et al., 2014; Rattani et al., 2014; Vázquez-Novelle et al., 2014). (C) Kinetochore recruitment and exclusion of the chromosomal passenger complex (CPC), which includes Aurora B and Survivin, depend on nonproteolytic ubiquitylation. Exclusion of PLK1 from the kinetochore in case of bioriented microtubule attachments also depends on its ubiquitylation. (D and E) Microtubule transport can be promoted by cargo ubiquitylation, as is the case for the spindle assembly factor NuMA and Aurora B. Whether the ubiquitylation of PLK1 promotes its transport to the spindle midzone has not yet been determined. Red crosses depict targets of proteasomal degradation, red circles depict ubiquitin, and purple circles depict Aurora B kinase.