FIG. 1. .

Cyclic AMP stimulates cell-cell fusion in full length Cx43-expressing cell lines. Two-color cell fusion assay was performed using wild-type Jeg3 (A and B), αhCG/Cx43 (C and D), JpUHD/Cx43 (E and F), and JpUHD/trCx43 (G and H) cell lines. Cells were stimulated with control serum-free medium (A, C, E, and F) or 1 μM 8-bromo-cAMP (B, D, F, and H) for 48 h. Cell-cell fusion, indicated by the mixing of the red and green dyes to give either red nuclei surrounded by green cytoplasm or green nuclei surrounded by red cytoplasm, can be observed in the cAMP-treated αhCG/Cx43 (fine arrows, D) and JpUHD/Cx43 (bold arrows, F) cells. Bar = 25 μm.