NFAT Activation Inhibitor III (INCA-6) is a potent and selective inhibitor of calcineurin-NFAT (Nuclear Factor of Activated T cells) signaling. A quinone based compound that is cellularly permeable and blocks NFAT dephosphorylation. In experiments, this product particularly showed ability to prevent transient outward K+ current reduction in 3-Hz paced left ventricular cardiomyocytes following tachycardia. NFAT Activation Inhibitor III does not exhibit effects on calcineurin activity or on calcineurin’s downstream signaling.