Movie 1

Microtubules are required for the centralization of antigen-bound BCRs into a cSMAC. A20/D1.3 were cells stained with Cell Trace Far Red (blue) and pretreated with either DMSO or 5 μM nocodazole for 5 min before being allowed to settle on adherent Cos-7 APCs expressing HEL-GFP (green). Time-lapse spinning disk confocal microscopy was used to acquire images every 12 s starting at 1 min after adding B cells to the APCs and continuing until t = 12 min. The video is played back at 5 frames per second (60X real time).