ESR1 and breast neoplasm: Several findings supported GRPR’s dependence on ERα: the increased GRPR levels in ERα-positive compared with ERα-negative breast tumours (Extended Data Fig. 10e); the strong correlation between GRPR mRNA and ERα activation score (Extended Data Fig. 10f); and ERα binding to active regions associated with the GRPR promoter (Extended Data Fig. 10g,h).