FGF10 and breast cancer: Moreover, there has already been strong evidence that the isoform IIIb and not isoform IIIc of FGFR2 is associated with breast cancer development, since FGF10, the main ligand of FGFR2-IIIb and not FGFR2-IIIc, is amplified in approximately 10% of breast cancers and genome-wide association studies identified variants near FGF10 as a genetic risk factor for breast cancer susceptibility, possibly influencing FGF10 expression [6].