Although several previous studies have now examined Ecrg4 gene expression in cancer, bone development, and more recently CNS aging, the studies described here provide the first functional in vivo demonstration that Ecrg4 expression is (1) necessary for normal CNS development, (2) involved in the CNS injury response in mammals and (3) regulates cell fate in the sub-ependymal zone. This evidence concerns the gene ECRG4 and cancer.