“…In addition, we recently demonstrated that cingulate callosal axons also express the axon guidance receptor DCC, and that these axons are attracted towards its ligand, NTN1, at the midline (Fothergill et al, 2014). Similarly, other short-and longrange axon guidance molecules have been demonstrated to function in regulating neocortical callosal pathfinding (Shu and Richards, 2001;Shu et al, 2003;Andrews et al, 2006;Islam et al, 2009;Nishikimi et al, 2011). As callosal axons from the dorso-lateral cortex, where Nrp1 expression is absent, are able to project their axons medially (Zhou et al, 2013), it appears likely that other axon guidance mechanisms can guide callosal pathfinding in the absence of Nrp1 expression.…”