Slit2N collapses only OB axons. Collapse assay of E15 olfactory bulb (A, B) and DRG (C, D) growth cones. A, Histogram showing that Slit2-N-expressing membranes significantly induced growth cone collapse compared with control membranes or Slit2-U-expressing membranes. B, Slit2-N proteins (2 μg/ml) significantly induced growth cone collapse (p = 0.003) compared with control (CTL), Slit2-U, or Slit2-C. C, Neither of the different Slit2-fragment-expressing membranes significantly induces DRG growth cone collapse. D, The level of DRG growth cone collapse is insignificant with the different Slit2 fragments tested at 2 μg/ml. E, Dose–response curve of the collapsing activity of the various Slit2 fragments on OB and DRG growth cones.