Down-regulation of extracellular signal-regulated kinase 1/2 activity in P-glycoprotein-mediated multidrug resistant hepatocellular carcinoma cells

Figure 4 ERK1 and ERK2 mRNA expression in MDR and parental cells. ERK1 and ERK2 mRNA levels were measured by QRT-PCR. A: HepG2/ADM and HepG2 cells; B: SMMC7721/ADM and SMMC7721 cells. Results were normalized by β-actin mRNA expression and compared with the levels in parental cells (n = 3). The results are shown as mean ± SE. Statistical analyses comparing MDR cells with parental cells were performed using Student's t-test. ^bP < 0.01 vs parental cells (data not shown).