HIF1A and breast cancer: In addition, we compared the expression levels of ESM-1, HIF-1α, and LOX in these three cell populations, based on a report indicating that the HIF-1α/LOX pathway plays a key role in promoting breast tumor growth and metastasis [26] and our previous observation that overexpression of ESM-1 in RT-R-breast cancer cells was involved in enhanced tumor progression [27].