[2] During embryogenesis, fasII is dynamically expressed on a subset of axon fascicles in longitudinal nervous system pathways,[3] including the MP1 tract.
[2] Later, fasII is expressed on growth cones of axons in other tracts including embryonic peripheral nervous system (PNS) motor neurons.
[2] FasII is also expressed by clusters of differentiating neuroblasts at early stages of neurogenesis where its function is not fully understood but might be involved in proneural gene induction.
[2] Other roles for fasII include delineating two axonal pathways in the adult ocellar sensory system (OSS) via its expression on ocellar pioneer (OP) neurons where it acts to promote neurite outgrowth from primary neurons (along with neuroglian) by activating fibroblast growth factor receptor (FGFR) signaling.
[2] In addition, fasII has been shown to be involved in synaptic target selection, stabilization and remodeling along with several proteins such as netrins, semaphorins and other Ig-CAMs.