Figure 1.

Cx43 expression in Cx43^+/+ and Cx43^+/− lungs. (A) Cx43 expression was detected by Western blot in Cx43^+/+ and Cx43^+/− lung homogenates. Using an antibody against the C-terminus of Cx43, three isoforms of 46, 43 and 41 kD were detected; Cx43^+/− lungs express 61% less Cx43. The specificity of the Cx43 antibody was verified on lung extracts from Cx43^K258stop/− mice. As expected, the antibody no longer recognized the three forms of Cx43 in the absence of its immunogenic C-terminus motif. The 46, 43 and 41 kD forms of Cx43 are indicated at the right of the gel. (B) The Cx43/β-actin signals were quantified from five lungs per condition. (C) Cx43 was detected by Western blot using a polyclonal and a monoclonal antibody in control cells (Cont) from mouse and human origins, respectively. However, no Cx43 expression was seen in murine and human neutrophils. Note that blots were combined from separate gels. **Indicates P < 0.01. D) Cell-to-cell diffusion of neurobiotin was demonstrated in Cx43^K258stop-expressing cells but not in the parental N2A cells. Phase-contrast images of the corresponding fields are also shown. Scale bar represents 40 μm.