UK-78282 blocks both Kv1.3 and Kv1.4. Kv1.3 and Kv1.4 are members of the Shaker family of voltage-gated potassium channels. Kv1.3 is expressed in brain and in effector memory T (Tem) cells, and Kv1.4 is expressed in brain. Both channels are involved in setting the membrane potential of neurons. In addition, Kv1.3 maintains the membrane potential for T memory cells and is up-regulated upon T cell activation, contributing to multiple immune processes and disorders. Blockers of Kv1.3 have long been sought for therapeutic benefit, and they are also valuable tools for studying the immune system. Selective blockers of Kv1.4 are desired, as there are few if any currently available. UK-78282 is valuable for immune system studies, where the absence of Kv1.4 makes it functionally selective for Kv1.3, and it has shown suppression of T cell activation. UK-78282 is also valuable for the study of Kv1.4 function.