Movie S4.

Elongation and Xac2-induced filament severing of stuck F-actin (Fig. 1D). Stuck F-actin grows from immobilized mDia1. After the pointed end side is trapped, elongation of stuck F-actin stops without forming a bent loop. This F-actin was not severed for 500 sec in the presence of 50 nM Xac2. Scale bar is 5 μm.