Altered effect of mutant GATA3 in breast cancer leads to a distinct expression pattern of GATA3 target genes. (A) mutGATA3 fails to activate GATA3 dependent promoter. GFP construct driven by GATA3 responsive promoter was cotransfected with the indicated constructs into HeLa cells and the fluorescence levels measured after 48 hours. Representative results of three independent experiments are shown. In each section, the red curve represents GFP transfected cells; the blue curve represents GFP with mut- or wtGATA3, as indicated. (B) mutGATA3 has an altered effect in breast cancer cells. Relative transcript levels of GATA3 target genes after transfection of wtGATA-3 or mutGATA-3 into MCF7 cells. Results shown are average ± standard error of three to four independent experiments. GATA3, GATA binding protein 3; mut, mutant; wt, wild type. (*) P-value <0.1 (**) P-value <0.005.