Hsc70 is required for netrin-1–dependent attraction of embryonic cortical neurons. Control (siCTL) or Hsc70 siRNA (siHsc70) was electroporated with a GFP reporter plasmid in E17.5 cortical neurons. At DIV2, neurons were exposed to vehicle PBS or a 200-ng/ml netrin-1 VI-V (net) gradient in Dunn chamber turning assays. (A) Video time-lapse imaging of control neurons exposed to a gradient for 90 min. Bar, 20 µm. (B) Rose histograms represent the distribution of turning angles of the cortical neurons. Green or pink indicate positive or negative turning angles, respectively. (C) Mean turning angles for each condition (>50 axons per condition, from at least three independent experiments). Error bars indicate the SEM (NS, P > 0.05; *, P < 0.05; **, P < 0.01; one-way ANOVA, Newman-Keuls multiple comparisons test). (D) The mean displacement of turning cortical growth cones over the 90-min imaging period. Error bars indicate the SEM (n > 50 axons per condition; NS, P > 0.05; ***, P < 0.001; one-way ANOVA, Newman-Keuls multiple comparisons test). (E) The mean displacement of all cortical growth cones over the 90-min imaging period (>70 axons per condition, from at least three independent experiments). Error bars indicate the SEM (***, P < 0.001; unpaired student’s t test). (F) The distribution of growth cone displacements from E. (G) The proportion of growth cones from E with at least one retraction event. (H) The proportion of neurons from E with collapsed growth cones.