Diffusion-restricted hypoxia (also called chronic hypoxia) mainly mediated by HIF-2α refers to the sustained restriction in oxygen diffusion by abnormal vascular network (Nejad et al., 2021) LOXL2 coexpress Snail1 and is related to Twist transcription in breast cancer, thereby may be intimately involved in the process of EMT. This evidence concerns the gene EPAS1 and breast cancer.