Syb2 is required for Sema3A-mediated repulsion, but not Sema3C-mediated attraction, in dissociated neurons. (A) E15 dissociated cortical neurons were grown in Ibidi microchambers in medium with or without BoNT/D. At t = 0 h, 3 µg/ml of control, Sema3C-Fc, or Sema3A-Fc medium was added at the top of the chamber. Axons were allowed to grow and turn for 3 h. Bar, 10 µm. (B) Mean values ± SEM (error bars) of axonal turning in each condition (control, n = 136; control + BoNT/D, n = 91; Sema3C, n = 41; Sema3C + BoNT/D, n = 39; Sema3A, n = 81; Sema3A + BoNT/D, n = 105 axons). **, P < 0.005 by Student’s t test.