Fig. 2. Staining of a resealed fibroblast with antibodies against a luminal domain of the lyososome-specific protein, Lamp-1. The right hand side of this cell was severed when the culture dish it was growing in was scratched with a needle (the red streak on the right indicates the needle path). Staining with anti-Lamp-1 was then performed on the living, resealed cell, limiting detection to surface exposed antigen only. Surface exposure of Lamp-1, indicated by the staining, is evident over the resealed disruption site. This provides strong evidence that the local exocytotic response evoked by a disruption utilizes lysosomes. (Photomicrograph courtesy of Norma Andrews, Yale University.)