IDO1 promoter methylation regulates IDO1 gene expression. A and B, Analysis of IDO1 mRNA expression by qRT-PCR in time course treatment of MCF7 and MDA-MB-231 cells with IFNγ (50ng/mL). C, ChIP analysis of RNA Poll II at IDO1 gene promoter in MDA-MB-231 cells after treatment with IFNγ for 4hr. D, ChIP analysis of RNA Pol II at IDO1 gene promoter in MCF7 cells after time course treatment with IFNγ for up to 8hr. E and F, qRT-PCR analysis of IDO1 expression in MDA-MB-231 (E) and MCF7 (F) cells after treatment with 5-azadC (2μM) for three days followed by IFNγ stimulation overnight. G, Luciferase reporter activity measured in MDA-MB-231 and MCF7 cells transfected with methylated or unmethylated IDO1 promoter reporter constructs after treatment with or without IFNγ. Data in this figure are shown by mean ± SEM from three independent measurements. Results are representative of at least two independent experiments.