Association of Borealin with endogenous INCENP. Asynchronously growing and mitotic WT-8 lysates were incubated with antibodies to endogenous INCENP or p53 (negative control) for immunoprecipitation and subsequently analyzed by Western blotting (WB) using an antibody to the Flag-tag. Transfers were stripped and probed for INCENP and β-actin as loading control. I: Interphase, M: Mitotic. Shift controls are Hela cells, asynchronously growing or blocked in mitosis with nocodazole and lysed with RIPA buffer. These were included as an internal conformation for the mobility shift and whether electrophoresis was sufficient.