Hormone‐responsive breast cancers are also receptive to FGF signalling, where studies have shown that FGF overexpression can promote oestrogen‐independent proliferation in ER+ breast cancers,65 and that signalling by FGFR2 may confer resistance to tamoxifen through degradation of ER,56, 66 or even that oestrogen may mediate FGF paracrine activation.67 Here, ESR1 is linked to breast carcinoma.