Kv3.1, Kv3.3, and Kv3.4 belong to the Kv3 subfamily, which is a class of Kv channels characterized by positively shifted voltage dependencies and very fast deactivation rates [30], and these Kv channels were examined as tumor hypoxia-related Kv channels in A549, MDA-MB-23, and HT-29 cells, which are highly aggressive lung, breast, and colon cancer cell lines, and all three cell lines expressed Kv3.1, Kv3.3, and Kv3.4. This evidence concerns the gene KCNC1 and malignant colon neoplasm.