Thus, pharmacological activation of KCa3.1 may enhance antitumor activity of CD8+ T‐cells by overcoming the inhibition of the KCa3.1 activity caused by large amounts of adenosine in cancer stroma and/or localized down-regulation of membrane-proximal calmodulin, the Ca2+ sensor of KCa3.1. This evidence concerns the gene KCNN4 and cancer.