Fig. 1. FCS analysis of F-dexa in a single AtT-20 cell. (A) The confocal volume was positioned above the center of a cell and a z-intensity scan was performed towards the glass surface. Representative positions, (a) outside of the cell (in the solution), (b) inside the cytoplasm and (c) at the cell membrane, are indicated by horizontal lines. (B) Intensity fluctuations were recorded for 30 seconds and are shown for the three representative positions together with their normalized autocorrelation curves (C). Data were fitted with the three component model.