KN-92 hydrochloride is primarily used in research settings as a selective inhibitor of calmodulin-dependent protein kinase II (CaMKII). It is particularly valuable in studying the role of CaMKII in various cellular processes, including neuronal signaling, memory formation, and cardiac function. Researchers utilize this compound to investigate the mechanisms underlying conditions such as heart disease, neurological disorders, and synaptic plasticity. By inhibiting CaMKII, KN-92 hydrochloride helps elucidate the enzyme's involvement in these physiological and pathological processes, contributing to the development of potential therapeutic strategies.