In later stages, 5 to 7 days after stroke onset, Tregs infiltrate the brain parenchyma, prevent microglia/macrophage polarization toward the M1 phenotype, driving microglial polarization toward the M2 phenotype, and inhibit astrocytic activation through the amphiregulin (AREG)/epidermal growth factor receptor (EGFR) pathway [115,116]. The gene discussed is AREG; the disease is stroke disorder.