Figure 9.

Arp2/3 activity is not necessary for efficient guidance and insufficient to trigger growth cone turning on laminin. E7 DRG explants were grown on laminin and treated with DMSO or 50 μm CK666 4 h before the turning assay. An NGF gradient was established with a micropipette located at 45° and ∼80 μm from the growth cone leading edge. a–d, Representative images of DRG growth cones 1 min before and 45 min after positioning the micropipette. e. f, Growth cone turning angle quantification. g, Growth cone turning angle quantification in response to a gradient of Chariot complexed to VCA-GST or β-galactosidase as a control, delivered as above. h, k, Boundary assay for control (DMSO) and Arp2/3-inhibited (CK666) retina explants (left) with alternating lanes of laminin (black) and ephrin A2 + laminin (magenta) with axons stained with antibodies against the neuronal β3-tubulin (green). i, j, l, Show axons in close apposition to the ephrin A2 + laminin lanes at higher magnification.