Fig. 8. Metaphase arrest activates Bfa1/Bub2 to inhibit Tem1 and shut down the MEN. (A) Metaphase arrest induced by SAC activation or the apc2-8 mutation leads to a presumed activating phosphorylation of Bfa1. This Bfa1 phosphorylation, together with phosphorylation of Lte1, inactivate Tem1 to block activation of the MEN (including Dbf2) and cytokinesis (Frenz et al., 2000). (B) Bub2/Bfa1 control of Tem1 is rate limiting in metaphase to block MEN activation. Lte1 positive control of Tem1 occurs in anaphase and promotes mitotic exit.