ESR1 and breast carcinoma: Aberrant activation of FGF/FGFR signaling caused by FGF overexpression or FGFR1 amplification and overexpression in ER+ breast cancer cells is associated with estrogen-independent cell proliferation, metastasis and reduced distant metastasis-free survival (McLeskey et al., 1998; Turner and Grose, 2010).