E2-inducible genes are enriched in ER+/PR+ breast tumors compared to ER+/PR- breast tumors. Expression patterns for the cluster B genes (induced by E2 in vitro within 4 hours; Figure 1a) are shown alongside the corresponding patterns in MCF-7 xenografts (Figure 1b) and in two independent breast tumor datasets from van de Vijver et al.  and Wang et al. . Genes showing significant correlation with PGR in both van de Vijver and Wang datasets (p < 0.05 in each) are highlighted and listed: italics indicate more highly expressed in ER+ compared to ER- tumors (p < 0.01); bold type indicates significantly correlated with age-corrected ER expression (p < 0.05; see Figure 2). Enrichment p value by one-sided Fisher's exact test.