Motif over-representation of differentially expressed transcription factors. Over-representation statistics for each cluster profile of the 16 binding motifs contained in TRANSFAC representing the 6 differentially expressed transcription factors: ATF3, ATF4, E2F1, FOXO1, MYC, SP1. A. Heatmap of Z scores organized by two-way hierarchical clustering according to the Z score pattern across binding motifs and cluster profiles. For plotting purposes each Z score vector was normalized to unit variance. Over-represented genes are highlighted in red while under-represented transcription factors are shown in green (see color bar). It is clear that consensus clusters 1-4 and 6-11 group together, sharing common over- as well as under-represented transcription factor motifs. It is also striking that motifs over-represented in these groups typically will be under-represented in the other and vice versa. Consensus clusters 5 and 12 have different patterns of binding motifs Z scores. B. Principal components of the Z score vectors of each consensus cluster (columns of A) validate the pattern observed in A: cluster profiles 1-4 and 6-11 are closely grouped while cluster profiles 5 and 12 are separated from these.