passages.id: split_6_test_1805_passage
passages.type: progene_text
passages.text: While improper spindle orientation activates the Bub2 / Bfa1 - dependent checkpoint in budding yeast , delaying exit from mitosis , lack of bipolar kinetochore - microtubule attachment activates a signal transduction cascade that prevents both anaphase onset and exit from mitosis by inhibiting the Cdc20 / APC ( Anaphase Promoting Complex ) - mediated proteolysis of securin and inactivation of mitotic cyclin - dependent kinases ( CDKs ) , respectively .