Recent studies have identified several genes that under long-range regulation during breast cancer progression, including those encoding transcription factors such as ER [29,30], PR [31], AP1 [32], AP2 [33], FoxA1 [34,35], GATA3 [36,37], architectural components such as cohesion [38,39] and SATB1 [40,41], coactivators such as p300/CBP [42,43] and SRC1-3 [44]. The gene discussed is ESR1; the disease is breast cancer.