POD-GFP or GFP protein was applied to the skin for 24 hours. Whereas GFP does not bind skin beyond that of auto fluorescence, POD-GFP binds to the epidermis (a). Although hair (arrowhead) and papilla of the hair are also GFP-positive in sections exposed to POD-GFP, a significant portion of this signal is due to auto fluorescence (b). E, Epidermis; P, Papilla. Untreated, n = 3, POD-GFP and GFP, n = 4. Color version of this figure appears online.