A study found that PI3K/AKT/mTOR pathway resulted in the overexpression of immunorelated genes (PD‐L1, CSF1, and CSF1R) or cytotoxic T lymphocyte‐associated protein 4 (CTLA4) in microglia or cancer cells in the microenvironment of brain metastases. The gene discussed is MTOR; the disease is cancer.