Knockdown of NetB through expression of NetB^{dsRNA.Scer\UAS} in photoreceptor axons (under the control of Scer\GAL4^{Scer\FRT.Act5C} and Scer\FLP1^ey.3.5.hs) does not cause any R8 axon-targeting errors. Knockdown in the target area (through expression under the control of Scer\FLP1^ey.3.5.hs, Scer\GAL80^ey.3.5, Scer\GAL4^{Scer\FRT.Act5C} and Scer\GAL4^GMR.long) results in R8 axons stalling at the medulla neuropil border instead of terminating in the M3 layer.