The k-fibers persistently lengthen under applied force, related to Fig. 2. Microneedle manipulation of individual k-fiber in metaphase PtK2 cell results in k-fiber (SiR-tubulin, white) lengthening and spindle translation and rotation in response to force. The microneedle (Alexa 555, yellow) exerts force for minutes starting at t = 0. Scale bar, 4 µm. Video was collected using a spinning disk confocal microscope at 1 frame every 10 s. Video has been adjusted to play back at a constant rate of 15 frames/s. Video corresponds to still images from Fig. 2 B.
