The MP1 pathway does not form in Fas2^EB112 mutant embryos: at embryonic stage 12/1 the dMP2 and MP1 growth cones do not turn posteriorly (which happens in the wild-type) but rather project laterally for a short distance. Also, the vMP2 growth cone often turns anteriorly (as in the wild-type) but already shows variability in the precise orientation of its tip. The MP1, dMP2 and vMP2 growth cones stay stalled in the same position through to stage 14 in mutant embryos, in contrast to the wild-type.