Compared with other members of the FGF family, such as FGF9, its expression in BC is not significant.[48] Research has found that FGF20 is expressed in embryonic mammary glands and is an important mediator in the morphogenesis of mammary gland budding and branching.[49] The exact molecular mechanisms of FGF20 influence on mammary morphogenesis are yet to be fully elucidated. The gene discussed is FGF9; the disease is breast cancer.