Cohesin complexes dissociate from chromosomal arms in prometaphase, leading to sister chromatid resolution. Sister chromatid resolution involves separation of sister chromosomal arms while cohesion at sister centromeres persists (Losada et al. 1998, Hauf et al. 2001, Hauf et al. 2005). Cohesin and CDCA5 (Sororin) simultaneously dissociate from chromosomal arms in prometaphase (Nishiyama et al. 2010, Zhang et al. 2011). This process, triggered by CDK1-mediated phosphorylation of CDCA5 (Dreier et al. 2011, Zhang et al. 2011) and PLK1-mediated phosphorylation of the STAG2 cohesin subunit (Hauf et al. 2005), is controlled by WAPAL (Gandhi et al. 2006, Kueng et al. 2006, Shintomi and Hirano 2009). WAPAL controls cohesion of sister chromatids likely through competing with CDCA5 for binding to cohesin-associated PDS5 (PDS5A and PDS5B) (Nishiyama et al. 2010). While the interaction of WAPAL with PDS5 depends on CDCA5 (Nishiyama et al. 2010), WAPAL maintains its association with cohesin through interaction with cohesin subunits (Kueng et al. 2006, Shintomi and Hirano 2009).