Soluble tubulin passively diffuses into the nuclear space at NEB. (A) FRAP of GFP–α-tubulin in the nuclear region of mitotic S2 cells after MT depolymerization with colchicine. Bleaching was conducted at time 00:00 (minutes:seconds). The relative fluorescence (nuclear/cytoplasm) was set to 1 before bleaching. Data points represent means obtained from 10 cells, error bars represent standard deviations. Soluble tubulin is highly mobile and exchanges between compartments (t_1/2 = 4.495 s; SD = 1.552 s; recovery = 98.5%; SD = 4.3%; n = 10 cells). (B) Laser microsurgery in an interphase S2 cell expressing Megator-mCherry and GFP–α-tubulin after MT depolymerization with colchicine. The arrowhead indicates the cut region. Membrane blebbing was occasionally observed in the cut region (arrow). Time is given in minutes:seconds, relative to laser microsurgery. Bars, 10 µm.