PEA3 regulates Notch-1 and Notch-4 in different subtypes of breast cancer. (A) through (C) MDA-MB-231, MCF-7, BT474 and SKBr3 cells were transfected with either scrambled or PEA3 siRNAa. Once normalized to MDA-MB-231 cells, the transcript levels of PEA3 (A), Notch-1 (A) and Notch-4 (C) were compared and measured by quantitative real-time PCR. BT474 cells (D) and SKBr3 cells (E) were transfected with either empty vector or PEA3 expression plasmid. Notch-1 and Notch-4 mRNA levels were normalized to empty vector and measured by quantitative PCR. Means and standard deviations of three experiments were plotted. Statistical significance was determined by performing a two-tailed, unpaired Student's t-test.