Mice were bred and maintained in the Uniformed Services University of the Health Sciences (USUHS) animal housing facility and all procedures were performed in accordance with guidelines of the National Institutes of Health, the Society for Neuroscience, and the USUHS Institutional Animal Care and Use Committee. FGF2 knockout mice on the 129 Sv-Ev:Black Swiss genetic background were obtained from breeding heterozygous pairs (provided by Dr. Doetschman, University of Cincinnati). This FGF2 knockout was generated by a targeted deletion replacing a 0.5-kb portion of the FGF2 gene, including 121 bp of the promoter and the entire first exon with an Hprt minigene (17) .