Figure 6.

Knockdown or overexpression of EGFR can lead to changes in the activation rates of EGFR downstream signaling pathways in Caco-2 cells. In Caco-2 cells, siRNA and recombinant plasmids were used to knock down and overexpress EGFR, respectively. (A,D) The protein content of cellular total and phosphorylated EGFR, MEK, ERK, MKK and JNK contents were determined by western blotting after knockdown (A) and overexpression of EGFR (D). (B,E) The semi-quantitative analysis of cellular total and phosphorylated EGFR, MEK, ERK, MKK and JNK contents was performed based on the relative density values of the bands of western blotting. The relative density value of the control group was set to one. (C,F) qPCR was used to measure the mRNA expression of EGFR, MEK, ERK, MKK and JNK in EGFR knockdown groups (C) and EGFR overexpression group (F) relative to the control group. The relative mRNA expression of the control group was set to one. Each bar represents the mean ± SEM. All data were derived from at least three separate experiments. *, P<0.05; **, P<0.01; ***, P<0.001. EGFR, epidermal growth factor receptor; siRNA, small interfering RNA; MEK, mitogen-activated protein kinase kinase; ERK, extracellular regulated protein kinase; MKK, MEK 4/7; JNK, c-Jun N-terminal kinase; qPCR, quantitative real time polymerase chain reaction; SEM, standard error of mean.