To that end, our group reported characterization of intricate relationships among breast cancer, astroglial and microglial cells where astrocyte-released exosomes transfer PTEN-targeting microRNA into cancer cells to mediate PTEN down-regulation in the cancer cells, which ultimately results in CCL2 up-regulation and recruitment of brain metastasis-promoting monocytes [58]. The gene discussed is PTEN; the disease is cancer.