FGF-2 inhibits breast cancer cell proliferation and response to chemotherapy through the activation of ERK [122], phosphoinositol-3 kinase (PI3K) [98,119] and intracellular TGF-β-mediated upregulation of cyclin-dependent kinase inhibitors p21Waf1, p27Kip1 and 15INK4b [123,124], inactivation of CDK2 and CDK4, and dephosphorylation of retinoblastoma protein (Rb) [123], mechanisms which have been confirmed in subsequent investigations [114,115]. Here, PIK3CA is linked to breast cancer.