Updated project metadata. In late mitosis, the timely polyubiquitylation and subsequent degradation of securin and cyclin B by anaphase-promoting complex/cyclosome (APC/C) play a critical role for anaphase onset and chromosome segregation. Binding of Cdc20, the co-activator of the APC/C, is critical for activation of APC/C at anaphase entry. We found that one MAPK, Pmk1, is involved in phosphorylation of Slp1Cdc20 (the Cdc20 homologue in the fission yeast Schizosaccharomyces pombe), which may promote its ubiquitylation and subsequent degradation, and thus impede APC/C activation and anaphase entry. To gain a full picture of Pmk1-dependent phosphosite map of Slp1Cdc20, we purified the APC/C-associated Slp1Cdc20 by immunoprecipitation of one APC/C subunit Apc15 in metaphase-arrested nda3-km311 cells. Apc15-GFP was purified from wild type, pek1DD [i.e. pek1(S234D,T238D)] and pmk1∆ cells respectively. Samples were separated by SDS-PAGE, and Coomassie blue-stained gel slices were excised and submitted for mass spectrometry analyses.