Table 1.

Activities of Shh and Wnts in vertebrate axon guidance.

Ligand(s)	Receptor(s)	Model	Animal	Activity	References
Shh	Boc/Smo	Pre-crossing commissural axons	Rodents	Attraction	Charron et al., 2003; Okada et al., 2006
Shh	Smo + ?	mDN axons	Mouse	Attraction	Hammond et al., 2009
Shh (low)	Ptc/Smo	RGC axons	Chick	Outgrowth	Kolpak et al., 2005; Fantetti and Fekete, 2012
		Statoacoustic ganglion axons
Shh	Hhip + ?	Post-crossing commissural axons	Chick	Repulsion	Bourikas et al., 2005
Shh	Boc	Ipsilateral RGC axons	Rodents	Repulsion	Fabre et al., 2010
Shh (high)	Ptc/Smo	RGC axons	Chick, Xenopus	Repulsion	Kolpak et al., 2005; Gordon et al., 2010; Fantetti and Fekete, 2012
		Statoacoustic ganglion axons	Chick
Shh	Ptc/Smo	Descending RST axons	Mouse	Repulsion	Song et al., 2012
Wnt4	Fz3	Post-crossing commissural axons	Rodents	Attraction	Lyuksyutova et al., 2003; Domanitskaya et al., 2010
Wnt5a/7a	?		Chick
Wnt1, Wnt5a	Ryk	CST axons	Mouse	Repulsion	Liu et al., 2005
Wnt3	Ryk	RGC axons	Chicken	Repulsion	Schmitt et al., 2006
	Fz			Attraction
Wnt5a	Ryk	Cortical axons	Mouse	Repulsion	Keeble et al., 2006
Wnt5a	Ryk/Fz	Cortical axons	Hamster	Repulsion	Li et al., 2009; Hutchins et al., 2011
Wnt5a	Ryk	Cortical axons	Hamster	Outgrowth	Li et al., 2009; Hutchins et al., 2011
Wnt5a	Fz3	mDN axons	Rodents	Repulsion	Blakely et al., 2011