ECRG4 and Hydrocephalus: The facts that (1) Ecrg4 expression is decreased following CNS injury, (2) Ecrg4 over-expression is growth inhibitory in the subependyma and (3) Ecrg4 gene knockdown induces a hydrocephalus phenotype in development, also suggest a novel role for augurin in the CP/ependymal biology.