E2F1 and breast cancer: We observed that the top five strongest TF co-occupancy pairs associated with breast cancer risk were FOXA1 + E2F1, FOXA1 + NR2F2, FOXA1 + ESR1, FOXA1 + SIN3, and FOXA1 + TCF12 (Fig. 2a, b and Supplementary Data 2).