ESR1 and breast cancer: Notable examples include a compelling set of signals for bladder cancer supported by both prostate epithelial cells and fetal ureteric bud cells, consistent with their common developmental origin and related epithelial lineages;45 and the association of bulk endometrial tumor tissue (UCEC) with ER+, but not ER–, breast cancer risk, corroborating known shared hormonal signaling pathways.46