Polo-like kinase required for mitotic exit; regulates mitotic spindle assembly, nuclear shape, and protein localization to the nucleolus and SPBs; controls targeting and activation of Rho1p at the division site via Rho1p-GEFs; role in adaptation to DNA damage promotes genome instability during replicative senescence; regulates meiotic commitment, spindle assembly, chiasmata formation, recombination intermediate resolution and SC disassembly; human homologs PLK1 and PLK3 complement cdc5 mutants