The intermediate conductance calcium-activated potassium channel KCNN4,also known as KCa3.1,IK1,or SK4,is a member of the potassium channel KCNN family. KCNN4 is expressed in T cells,mast cells,macrophages,erythrocytes,vascular smooth muscle cells,airway smooth muscle cells,intestinal and airway epithelial cells . Functionally,KCNN4 plays a key role in calcium-dependent cell functions,such as proliferation,activation,and migration,in a broad range of cell types .