ESR1 and breast cancer: DNA microarray and RNA sequencing analyses, for instance,have revealed the impact of estrogen on the expression of hundredsof genes.16−20 Additionally, chromatin immunoprecipitation (Chip)-sequencing andChip-microarray analyses have uncovered thousands of ERα-bindingsites in breast cancer cells.21−24 Moreover, proteomic methods have been employed toidentify ERα-regulated proteins in breast cancer cells.25 Despite these efforts, the genes and pathwaysresponsible for the physiological effects of estrogen remain elusive.