Figure 5

VEGF expression under glucose deprivation is induced by ATF4 but not Nrf2. A and D: mRNA expression of VEGF. A shows VEGF expression after ATF4 knockdown, and D shows VEGF expression after Nrf2 knockdown. The VEGF mRNA levels were normalized by the β-actin mRNA level at each point (VEGF/β-actin). The VEGF/β-actin values were calculated relative to the expression level at 0 h (the time of knockdown), which was set equal to 1. Bars indicate the standard deviation of independent triplicate measurements. B and E: Western blot analyses using an antibody against VEGF. + and – indicate the presence and absence, respectively, of glucose, control RNA, and ATF4 or Nrf2 siRNA. C and F: Measurement of VEGF protein secretion to the media. All RNA, protein and media amples were derived from HepG2 cells at 24 h after knockdown. * indicates that there is a significant difference (*: P < 0.05, **: P < 0.005).