Fig. 6. Bub1p becomes phosphorylated during meiosis I. (A) mei4 is required for exit from prophase I, and mes1 is required for entry into meiosis II. (B) Percentage of cells with 1 or 2 nuclei at each time point as scored by DAPI staining (left panel) and western blotting of cell extracts (right panel) from synchronous meiosis using pat1-114 mes1Δ strain. (C) Western blotting of extracts from pat1-114 and pat1-114 mei4Δ strains. Time after induction is indicated in hours.