Fig. 4.

Sequential abscissions on both flanks are observed in most NSC divisions and occur faster in Kif20b^−/− brains. (A and B) Using the same methods as in Fig. 3, scoring abscission by the disassembly of SiR-Tubulin on midbody flanks, the second abscission on the other flank was observable in more than 60% of NSCs in E11.5 and E13.5 cortices, regardless of genotype. (C and D) At E11.5, the second abscission was usually detected within 30 min of the first abscission in control NSCs but within 15 min in Kif20b^−/− NSCs. At E13.5, the second abscission was within 15 min in both control and mutant cells. Black and white arrows indicate medians (med) for control and mutant, respectively. (E and F) The total time from midbody formation to completion of bilateral abscissions is reduced in Kif20b mutant NSCs at both ages. Blue lines show means. (G) Cumulative frequency curves of total time to second abscissions of E11.5 and E13.5 Kif20b^−/− NSCs (dashed lines) are shifted to the left of control curves (solid lines). For E11.5, n = 34 +/+ (four brains), n = 56 Kif20b^−/− cells (four brains). For E13.5, n = 41 +/+ (five brains), n = 32 −/− cells (three brains). KS, Kolmogorov–Smirnov; MW, Mann–Whitney; n.s., not significant (Fisher’s exact test). *P < 0.05 (Student’s t test); ***P < 0.001 (Student’s t test).