Constitutively active Myosin Va, but not Myosin VI, is excluded from the axon in vivo. Spinal motoneuron in 2 dpf zebrafish expressing (A) GFP, (B) caMyoVa-mCherry, (C) caMyoVa-mCherry (purple) and GFP (green) (n = 9 neurons, 3 fish) (D) GFP, (E) caMyoVI-mCherry, (F) caMyoVI-mCherry (purple) and GFP (green) (n = 9 neurons, 3 fish). Scale bar 10 µm.