Fig. 2. Microtubule-independent motility of pigment granules. Shuttling motion of pigment granules was quantified in cells lacking microtubules. (a) Tracks of individual granules; granule positions were determined every 3 s for 300 s; tracks shown are for 100 steps; asterisk indicates the beginning and exclamation mark the end of a track. (b) Net displacement in 30 s. Net displacement was determined as the straight-line distance between starting and ending coordinates for each 30 s interval; n = 500 intervals for 50 granules each condition. Granules in control cells showed extensive motion whereas granules in cells treated with 2 µM cytochalasin D or 5 µM latrunculin showed reduced or virtually no motion, respectively.