Figure 3

EGFR signaling regulates cyclin D1 expression and β-catenin/TCF transcription activity. (A) Cyclin D1 expression increased when OECM1 cells were treated with EGF or LiCl (a GSK-3β inhibitor). (B) SAS cells treated with AG1478 or Erbitux had suppressed cyclin D1 expression. RNA and protein were isolated 24 h after treatment and subjected to RT-PCR and Western blotting. (C, D) TOP-FLASH or FOP-FLASH were transfected into OECM1 (C) or SAS (D) cells which were then treated with EGF, LiCl, AG1478, or Erbitux. Luciferase activity was determined after 24 h. Relative changes in expression are shown compared with the levels of FOP-FLASH in untreated (control) cells. Data represent means ± SDs of three independent experiments. Column, mean fold change; bar, SD.