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. Author manuscript; available in PMC: 2010 Jun 26.
Published in final edited form as: Mol Cell. 2009 Jun 26;34(6):663–673. doi: 10.1016/j.molcel.2009.04.029

Figure 2. p21 Upregulated the Protein Level of Nrf2 and its Downstream Genes.

Figure 2

(A) Knockdown of p21 diminished expression of the Nrf2-target genes in MEF-Nrf2+/+ cells. MEF-Nrf2+/+ cells were transfected with either control siRNA or p21-siRNA. The endogenous levels of p21 and Nrf2 proteins were detected by immunoblot analysis at 48 hrs post-transfection, while the mRNA expression of Nrf2, Keap1, NQO1 and HO-1 was measured 72 hrs after transfection. The error bars indicate standard deviations calculated from triplicate samples. *p<0.05 compared with its control. (B) Knockdown of p21 had no effects in MEF-Nrf2-/- cells. The same experiment was performed in MEF-Nrf2-/- cells as described in 2A. (C) p21 upregulated the ARE-reporter gene activity. HCT116-p21-/- cells were transfected with different amounts of p21 expression vectors, along with expression vectors for the NQO1-ARE firefly luciferase and TK-renilla luciferase. The protein levels of p21 and Nrf2 were detected with anti-p21 and anti-Nrf2 antibodies (lower panels). The firefly luciferase activities were normalized to renilla luciferase activities and the standard deviations were calculated from three independent experiments, each with duplicate samples. *p<0.05 compared with its control.