Fig. 3. cAMP dependency of PHCrac-GFP localization. Cells were incubated in buffer for 30 seconds, followed at t=0 seconds by perfusion with the indicated cAMP concentrations. At t=30 seconds, all cells were perfused with 1 µM cAMP. (A-E) The response at the boundary of a typical cell; the colours represent the differences between fluorescence intensity at the boundary and the cytosol. (F-J) The response in the cytosol, shown as the fluorescence intensity after stimulation relative to the fluorescence intensity before stimulation; the figure shows the means and standard deviations (large bars) and standard errors of the means (small bars) of about 20 cells. The experiment with 0.1 nM cAMP was slightly different: cells were stimulated for 45 seconds followed by the upshift. Because only about 15% of the cells responded to 0.1 nM cAMP with a patch, the fluorescence intensity in the cytosol (J) is presented for 18 cells without a patch (a) and two cells with a patch (b). (E) The response at the boundary in a cell with a patch. (D) The patch before cAMP stimulation is a bright cytosolic vesicle located next to the boundary.