Among the different types of channels, in particular, KCa3.1 but also the related KCa2.3 channel [71,72] of the same gene family, was found to be up-regulated in some but not all cancers and especially in those KCa3.1-expressing tumor cells showing high activity of MAP kinase cascades and AP-1 activity [17]. This evidence concerns the gene KCNN4 and cancer.