Characterization of Brca1 tumors (A) Pearson correlation coefficient matrix for pairwise comparisons of log-ratios among five spontaneous Brca1 tumors, based on 15,781 probes with reported values in at least 75% of samples (missing-value filter). (B) Unsupervised Hierarchical Cluster of 5 Brca1, 7 Brca1+/-, p53+/- IR and 10 Brca1Co/Co, p53+/-, MMTV-Cre (Furth) mammary tumors based on 339 genes filtered for present values and minimal variability of expression (see Materials and Methods). (C) The dendrogram corresponds to the summarized data for expression of keratins 5, 8,17,18,19 and 23, that were among the 339 genes. The color of each cell represents the relative expression level of each gene.(D) Unsupervised Hierarchical Cluster of original (0), first- (1) and second- (2) passage tumors based on the 416 probes that in addition to passing intensity and missing-value filters had a minimum 2.5-fold expression change in either direction from the median value in at least 20% of samples (Additional file 1).