Fig. 6.

PI3K activity inhibits phosphorylation of ERK 1/2: Immunoblot, using anti-phospho ERK1/2 (upper panel) and pan-specific ERK1/2 (lower panel) antibodies, of lysates from Cx43 coupled, v-src injected cells (lanes 2–5) treated with either Wortmannin (lane 3), U0126 (lane 4), or both (lane 5). In either the presence or absence of the MEK1/2 inhibitor, Wortmannin induced an increase in ERK phosphorylation. There was no significant change in the expression of ERK 1/2 in response to the inhibitors. The density of the bands was measured from several experiments, and expressed as a ratio of Phospho- to total ERK1/2 levels and plotted in a histogram below the gel. Inverted brackets indicate pair-wise statistical comparisons of results from three independent experiments yielding differences significant at the **P<0.001 (single asterisk) or the *P<0.05 level; analysis was performed by use of Student’s t-test.