FGF4 and breast cancer: Always in the context of BC, amplification of FGFR1- and/or 11q12-14, which is a chromosomal region containing CCND1, FGF3, FGF4, and FGF19, has been detected in 23% of hormone receptor-positive (HR+) BC, 27% Human Epidermal Growth Factor Receptor 2 (HER2)-positive BC, and 7% Triple Negative Breast Cancer (TNBC).