Figure 5: Association between RUNX1 and AXIN1 in ER⁺ breast cancer tumours.

(a) Correlation between the RUNX1 inhibitory index and AXIN1 mRNA in the breast cancer patient cohort of TCGA (ref. 20). The RUNX1 inhibitory index was calculated for each tumour as described in the ‘Methods’ section and the correlation with AXIN1 mRNA (UCSC isoform uc002cgp.1) was calculated. Bars represent the Pearson linear correlations (r) and P values were determined based on r and the sample size N. (b) Breast cancer tumour microarray TMA-1007 from Protein Biotechnologies, Inc. was immunostained for RUNX1 and AXIN1. The ER⁺ invasive ductal carcinomas were designated as positive or negative for RUNX1 and AXIN1. Data represent the odds ratio and the 95% confidence intervals for the association between AXIN1 status and RUNX1 status in tumours expressing ERα at either low (ER^low) or high levels (ER^high). Association between the RUNX1 status and AXIN1 status was tested using the Pearson chi-square test for the 2 × 2 table, for ER^low and ER^high tumours separately. Odds ratios for the ER^low and ER^high tumours were compared using the Breslow–Day test for homogeneity of odds ratios. (c) RUNX1 and AXIN1 immunohistochemical staining of two ER^high tumours from the TMA illustrating the association between RUNX1 and AXIN1 expression (Magnification × 20; scale bar, 50 μm; insets show the 1.1 mm cores in their entirety).