Figure 4.
Hyperactivation of ERK1/2 signaling downregulates Fbxw7β expression. (A) Quantitative PCR analysis of Fbxw7 isoforms mRNA levels in IEC-6 cells infected with vector, MEK1DD or H-RasV12. Results are expressed as mean ± SEM (n = 3). (B) Immunoblot analysis of Fbwx7 isoforms protein expression (n = 3). (C) Actinomycin D-chase analysis of Fbxw7β mRNA stability in IEC-6 cells infected with vector, MEK1DD or H-RasV12. Each point corresponds to the mean ± SEM of 3 individual experiments. (D) Effect of PD184352 on mRNA levels of Fbxw7 isoforms in IEC-6-H-RasV12 cells. Mean ± SEM (n = 3). (E) Effect of PD184352 on protein levels of Fbxw7β and Aurora A in IEC-6-H-RasV12 cells (n = 3). ***, P < 0.005.