ARNT and breast cancer: Thus, FOXA1 activates ER signaling and HIF2α, inducing a prometastatic program in BC [217], FOXO3a accumulates in cancer cells in an HIF1-dependent way [218], and FOXK2 inhibits the proliferation and invasion of BC cells and suppresses growth and metastasis in BC, repressing a cohort of genes, including HIF1β [219].