Differential regulation of Notch-4 by AP-1 members. (A) MDA-MB-231 cells were transfected with control, PEA3, Fra-1, c-JUN or c-FOS siRNA for 48 hours as described previously. Real-time PCR was performed to detect Notch-4 and HPRT transcripts. Transcript expression relative to control siRNA was calculated after normalization for HPRT transcripts. (B) Real-time PCR and Western blot analysis were performed to determine the efficacy of the specific siRNA. Means and standard deviations of three or more experiments were plotted. Statistical significance was determined by performing a two-tailed, unpaired Student's t-test for two comparisons and analysis of variance for multiple comparisons.