Differentially expressed proapoptotic and antiapoptotic genes in Notch1-IC/EREB, Notch2-IC/EREB, CAT/EREB, and EBNA2/EREB cells. (A) The heat map displays genes associated with anti- and proapoptotic functions, which were regulated at least 2-fold. Absolute expression values are compressed for better demonstration to −2 to +2. Red squares indicating a high (up to +2) expression, green (up to −2) a low expression, and black the mean (0) expression over the whole kinetics of all cell lines. Numbers and bars on the left side describe the clusters after hierarchical clustering. Gene symbols and gene names are depicted on the right side of the heat map. The cell lines are indicated above the heat map, as follows: N1-IC (Notch1-IC/EREB), N2-IC (Notch2-IC/EREB), CAT (CAT/EREB), and EBNA2 (CAT/EREB after addition of estrogen). The transcripts of which the expression was validated by quantitative RT-PCR are indicated by asterisks. Quantitative RT-PCR analysis of apoptotic (B) and antiapoptotic (C) genes: cells were deprived of estrogen for 3 days before doxycycline (Notch1-IC, Notch2-IC, CAT) or estrogen (EBNA2) addition. Total RNA was prepared from growth-arrested cells 0 hours, 8 hours, and 24 hours after doxycycline addition, and 4 hours and 24 hours after estrogen induction. mRNA expression was measured by qRT-PCR. mRNA levels are normalized to the transcriptional level of ribosomal protein genes and standardized to the time point of induction (0 hours), to calculate the fold induction at the different time points after doxycycline or estrogen addition. Values are representative of 3 independent qRT-PCRs of 3 biologic replicates. The analyzed genes are indicated above the diagrams; the coding of the graphs is elucidated beside the diagram: Notch1-IC (Notch1-IC/EREB), Notch2-IC (Notch2-IC/EREB), CAT (CAT/EREB), and EBNA2 (CAT/EREB after addition of estrogen).