We have previously demonstrated that KCa3.1 expression on glioma cells is involved in tumor cell migration in cerebral parenchyma.14 As KCa3.1 channels in the brain are also expressed by microglia and infiltrating macrophages (M/MΦ), we now investigated the effect of KCa3.1 blockage on M/MΦ cells, with particular interest on the acquisition of pro-tumor or antitumor phenotype. The gene discussed is KCNN4; the disease is central nervous system cancer.