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. Author manuscript; available in PMC: 2015 Apr 17.
Published in final edited form as: Nat Commun. 2014 Oct 17;5:5218. doi: 10.1038/ncomms6218

Figure 5. Stat3 induces the expression of ID1 to mediate the inhibitory effect of LIF on p53.

Figure 5

a. LIF induced ID1 expression in cultured cells. The mRNA and protein levels of ID1 were determined in HCT116 p53+/+-LIF, RKO p53+/+-LIF and their control cells. b. Stat3 induced ID1 expression in cultured cells. The mRNA and protein levels of ID1 were determined in HCT116 p53+/+ and RKO p53+/+ cells transfected with Stat3 expression vectors or control vectors. c. The induction of ID1 by LIF was largely blocked by Stattic. HCT116 p53+/+-LIF and their control cells were treated with 2 μM Stattic. The expression levels of ID1 were determined at both mRNA and protein levels. d. Ectopic ID1 expression by expression plasmid (pCMV-ID1) induced MDM2 expression as determined at both mRNA and protein levels in HCT116 p53+/+ cells. e. Ectopic ID1 expression decreased the activation and accumulation of p53 protein in response to 5-FU in HCT116 p53+/+ cells. f. Knockdown of endogenous ID1 by siRNA largely abolished the inhibitory effect of LIF on p53 activation and accumulation in response to 5-FU in HCT116 p53+/+ cells. The knockdown of ID1 was confirmed at the protein level (left panel). g. Knockdown of ID1 largely abolished the inhibitory effect of LIF on 5-FU-induced cell death in HCT116 p53+/+ cells. For a.–d. & g., data are presented as mean ± SD (n=3). *: p<0.001 (Student t-test).