FOS and breast cancer: In summary, we demonstrated that activation of the FGFR1 signaling robustly upregulates FOXQ1 expression through activating FGFR1-MEK-ERK2 to upregulate c-FOS and c-FOS-enhanced FOXQ1 gene promoter activity, and FOXQ1 plays an essential role in mediating the FGFR1 signaling-promoted breast cancer cell proliferation, colony formation and tumor growth (Fig.