Fig. 1. Effects of overexpressing APC on RAS-induced ERK pathway activation. (A) DLD-1 cells were transfected with 0.5 µg of the AP-1 (left panel) or ELK1 reporter (right panel) plasmids together with 0.5 µg of pCMV or pCMV-APC. Transfection with ELK1 trans-reporter was coupled with transfection with 0.5 µg of pFR-Luc or 25 ng of pFA2-ELK1 (Park et al., 2002). All cases except Mock (transfection with pCMV alone), were coupled with transfection with 0.1 µg of pMT3RAS-L61 (H-Ras-L61). Cells were harvested after 48 hours and the relative levels of expression of the reporters were measured by assaying luciferase. (B) DLD-1 cells were transfected with 0.5 µg of pCMV or pCMV-APC with or without 0.1 µg of pMT3RAS-L61. Cells were harvested after 72 hours. Western blot analyses were performed on whole-cell lysates to detect p-ERK, APC, ERK and -tubulin. The right bar graph shows quantitative analyses of the intensities of p-ERKs presented as the average of three independent identical experimental results from the left panel.