Beclin‐1 depletion prolongs prometaphase by delaying chromosome congression. (A-H) Time‐lapse films of HeLa cells stably expressing YFP‐α‐tubulin and H2B‐Cherry and treated with the indicated siRNA. The pictures are acquired every 10 min. Time lapse starts at nuclear envelope breakdown. (A) Mitosis in control cells. (B) Western blot of whole‐cell lysates from Control, Beclin‐1 and Beclin‐1+Mad2 siRNA‐treated cells. (C-E) Three different classes of mitotic progression were observed upon Beclin‐1 depletion. Higher magnification of lagging chromatids in the anaphase of Beclin‐1‐depleted cells is shown on the right of (D). 