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. 2010 May 14;12(9):956–966. doi: 10.1093/neuonc/noq045

Fig. 4.

Fig. 4.

HDMX depresses p21 expression by binding to TP53 consensus sites within the p21 promoter. (A) Both proximal and distal TP53 response elements in the p21 promoter are required to fully mediate the p53-dependent effects of HDMX. D54-HDMX cells were transfected with the indicated vectors and subsequently treated with 1.0 μg/mL tetracycline. Relative luciferase activity was measured after 24 h. (B) Transient overexpression of HDMX significantly reduces p21 promoter activity. HCT-116/p53+/+ and HCT-116/p53−/− cells were transfected with the indicated plasmids. Luciferase activity was measured 24 h after transfection. (C) siRNA knockdown of HDMX elevates p21 expression in TP53 wild-type cells, but has no effect on p21 expression in TP53-deficient cells. HCT-116/p53+/+ and HCT-116/p53−/− cells were transfected with the indicated siRNAs and immunoblotted with anti-HDMX and anti-p21 antibodies.