semar4dSemaphorin 4D (Sema4D) is a classic member of the semaphorin family involved in axonal guidance processes. The key effects of Sema4D in neurons are mediated by hh affinitySemaphorin 4D (Sema4D) is a classic member of the semaphorin family involved in axonal guidance processes. The key effects of Sema4D in neurons are mediated by hh affinity