Fig 6.

Residual pools of pERK2 remain following the siRNA knockdown of ERK isoforms. (A) Representative blot of cell lysates from siERK experiment (Fig. 4) probed with anti-pERK antibody. (B) Relative changes in the levels of pERK1 and pERK2 shown graphically, with columns representing the means ± SEM of the results of four independent experiments. All values were normalized to a value of 1 for pERK2 for cells treated with siCNL, and relative levels of pERK1 were corrected quantitatively for a 3-fold-greater sensitivity for the pERK antibody to detect pERK2 compared to pERK1 (see Materials and Methods). With siERK1, the P value for pERK1 was 0.0013; with siERK2, the P value for pERK2 was 0.0001; and with siERK1 plus siERK2, the P values for pERK1 and pERK2 were 0.0041 and 0.0001, respectively. Columns lacking asterisks did not reach a statistically significance difference compared to corresponding control values.