(A) Photomicrographs show immunofluorescent detection of the distributions of Cx40 in HeLa cells transiently transfected with wtCx40 or G38D. Cells were untreated (−) or exposed to 0.5µM epoxomicin (+) for 4 hours. Bar, 10 µm. (B) Photomicrographs show examples of the intercellular transfer of microinjected PI between HeLa cells transiently transfected with G38D. Cells were untreated (−) or exposed to 0.5µM epoxomicin (+) for 4 hours. GFP fluorescence (also expressed from the pTracer plasmid) allowed identification of the transfected cells. Arrows show injected cells. The bar graph shows the extent of dye transfer (PI containing neighbors) after injection of that tracer in cells transfected with wtCx40 or G38D. Cultures were untreated (−, white bars) or treated with 0.5µM epoxomicin (+, black bars).The extent of transfer was not statistically different between control wtCx40-expressing cells and those treated with epoxomicin. In HeLa cells transfected with G38D, transfer of PI was dramatically increased after epoxomicin treatment as compared to vehicle –treated control cultures (p<0.001). Epoxomicin treatment increased dye transfer in G38D–expresssing cells to levels comparable to those in cells expressing wtCx40. Values represent the mean + SEM, n=9−29.