Movie 3.

MDA-MB-231 cells can switch nuclear transit mechanism while passing through constrictions. Representative time-lapse sequence of an MDA-MB-231 cell expressing GFP-myosin IIA (cyan) and mCherrymyosin IIB (magenta) transiting through a ≤2×5 μm² constriction. In the left panel, the nucleus is outlined in yellow. After initially entering the constriction using a non-cortex driven mechanism (note the low myosin activity in the rear cortex), the cell exits and then re-enters the constriction with elevated myosin activity in the rear cortex, enabling successful nuclear transit. Scale bar: 10 μm.