A genome‐wide association study (GWAS) revealed that FGFR2, TNRC9, MAP3K1, and LSP1 were strongly associated with breast cancer risk.[30] A GWAS of invasive breast cancer in postmenopausal white women associated several FGFR2 alleles with the risk of sporadic postmenopausal breast cancer.[4] Other studies disclosed that FGFR2 is frequently upregulated in human breast cancers.[6, 31] Despite evidence implicating FGFR2 in breast cancer development, it is unknown whether FGFR2 activation induces breast cancer. Here, MAP3K1 is linked to breast cancer.