Fig. 1.

The effect of an increased dipole potential on the emission ratio of PPZ8 and F66. A–D: A431 (A, C) and SKBR-3 (B, D) cells were treated with the dipole potential-increasing sterol, 6-ketocholestanol, and control cells were treated only with Pluronic F-127. Cells were labeled with the dipole potential-sensitive indicators PPZ8 or F66, followed by determining the emission ratio on a pixel-by-pixel basis. Representative histograms display the distribution of pixelwise ratios calculated from single cells. The mean intensity ratios of control (Pluronic F-127) and 6-ketocholestanol-treated cells calculated from 20 to 30 cells are displayed (E, F). The error bars represent the standard errors of the mean. *P < 0.05, significant difference found between the control and 6-ketocholestanol-treated cells by three-way ANOVA, followed by Tukey’s honest significance test (HSD) test.