Cells were fixed and processed for immunocytochemistry. Monoclonal antibodies included A2B5 (1:300; Chemicon), III tubulin (1:3,000; Promega), BrdUrd (1:50; Becton Dickinson), 2',3' cyclic nucleotide 3'-phosphohydrolase (CNPase) (1:250; Chemicon), NeuN (1:50; Chemicon), O4 (1:150; Chemicon), and polysialylated neural cell adhesion molecule (PSA-NCAM) (1:400; Chemicon) and polyclonal antibodies Map-2 (1:30,000; a gift from Gerry Shaw, University of Florida), Dlx-2 (1:50; Santa Cruz Biotechnology), glutamic acid decarboxylase (GAD) 65/67 (1:125; Chemicon), and GFAP (1:600; DAKO).