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Fig. 4. Differential responses of wild-type Cx43 and Cx43-Y286A to both proteasomal
and lysosomal inhibitors. (A) The stable cell lines, Cx43-WT and Cx43-Y286A,
were treated for 3 hours with the proteasome inhibitor lactacystin (10 µM)
or the lysosomal inhibitors leupeptin (10 µM) or NH4Cl (10 mM).
Western blot analysis was then performed on the cellular lysates using either
an anti-Cx43 (top panel) or a ß-actin (bottom panel) antibody.
Steady-state levels of Cx43-Y286A were consistently greater than Cx43-WT,
therefore reduced fluorography was performed for comparative analysis. (B)
Quantitation of Cx43 protein levels in response to pharmacological agents.
Experiments were performed as in A, and the amounts of Cx43-NP (left panel)
and Cx43-P1,P2 (right panel) detected by western blot fluorography were
quantified using a molecular imager FX. Mean ± s.e.m. values of
normalised Cx43-WT (grey columns) and Cx43-Y286A (black columns) expression
levels are shown (n=3 independent experiments). Asterisks represent
P<0.01 versus control determined using the Student's
t-test.