STX12 and heart failure: A decrease in SERCA activity is strongly associated with the development and progression of heart failure.[48, 49, 50] Therefore, drugs that enhance SERCA2a activity such as enalapril, oxymatrine, and etomoxir, as well as SERCA2 viral gene delivery methods have been used to improve cardiac function and treat heart failure.[48, 49, 50] Indeed, CDN1163, an activator of SERCA, significantly mitigated cardiac dysfunction in cardiac‐specific Stx12‐deficient mice (Figure S8, Supporting Information).