Required specifically for chromosome disjunction during all mitoses; maternally provided protein is sufficient until mitosis 14 then zygotic protein is required. Involved in formation and/or maintenance of epithelial structures: bud extension during Malpighian tubule development, and foregut and hindgut morphogenesis (By similarity). Interacts with pim and Sse. Cleavage of thr contributes to inactivation of Sse (By similarity).