The antibodies used were commercially obtained. These were anti-calcitonin gene-related protein (CGRP; rabbit; 1:30; Chemicon/Millipore, Temecula, Californa AB5920), anti-GFP (chicken; 1:800, Aves Labs, Tigard, Oregon GFP-1020), anti-HA (rabbit; 1:200; HA.11 Covance, Princeton, New Jersey PRB-101P), anti-peripherin (rabbit; 1:100; Abcam, Cambridge, Massachusetts #1530), anti-S100beta (rabbit; 1:100; Abcam ab868), rabbit anti-beta-III tubulin (TUJ1; 1:3000; Covance MMS-435P). Detection of GFP offers superior sensitivity that is well over background fluorescence ( Fig. 1B and C) . For this study, some inconsistent signal detection or autoflourescence was occasionally observed and these sites identified in the individual figures. We find the expression of GFP and HA are similar, although anti-HA expression is detected predominantly on the surface of cells identified by anti-GFP expression (Fig. 1D ).