CD8A and cancer: PD‐L1 had the highest expression on EMT cells, that in addition to promoting the development of EMT in malignant epithelium, PD‐L1 imparted a potential immune suppressive character to cancer cells by binding to PD‐1 on CD8+T lymphocytes, expecially under hypoxic tumour microenvironment40, 41 (Figure 5H).