FIG. 4.

Enhancement of Cx26 and Cx43 expression is mainly translational. (A) Protein expression. BxC or Bx2 cell extracts were processed for Western blotting using a specific anti-Cx26 antibody (top), an anti-Cx43 antibody that recognizes both phosphorylated (pCx43) and unphosphorylated forms of Cx43 (middle), or a monoclonal anti-Cx43 antibody that recognizes Cx43 only when Ser368 is not phosphorylated (bottom). Membranes were also probed with an anti-β-tubulin antibody. Blots are representative of three separate experiments. Numbers are the mean ± standard error of the mean of densitometric quantifications of the three experiments normalized to β-tubulin, and are expressed as a ratio relative to the value obtained for BxC cells, which was set at 1. (B) Protein biosynthesis. Following pulse-labeling of cells, [³⁵S]methionine incorporation into total protein (top) or into immunoprecipitated Cx26 or Cx43 protein (bottom) was visualized by autoradiography of SDS-PAGE-separated and electrotransferred proteins, as described in Materials and Methods. (C) mRNA expression. The amount of Cx26 and Cx43 mRNAs was quantified by real-time quantitative PCR as described in Materials and Methods. Results are the means ± standard error of the mean of three separate experiments and are expressed as a ratio relative to the value obtained for BxC cells, which was set at 1.