Notably, miR‐27a‐3p was up‐regulated in breast cancer cells and exosomal miR‐27a‐3p derived from breast cancer cells induced by ER stress up‐regulated PD‐L1 expression, thereby causing immune evasion via the PTEN/AKT/PI3K axis (Figure 8). The gene discussed is CD274; the disease is breast carcinoma.