Compared with pharmacologic Kv1.3 inhibitors, such as 4-aminopyridine (4-AP) [25], tetraethylammonium (TEA) [25], and margatoxin (MgTX) [26], small interfering RNA (siRNA) is a more specific tool to investigate the role of Kv1.3 in cancer progression, as siRNA mediated knockdown of Kv1.3 resulted in reduced proliferation of tumor cell lines with less nonspecific responses [27]. The gene discussed is KCNA3; the disease is cancer.