In vitro studies were done where endothelin 1 and endothelin 3 was directly put in contact with reactive astrocytes in response to which this endothelin increases the number of astrocytes by process of mitosis, and upregulation of phospholipids was also observed; hence, a conclusive result was found which demonstrates that endothelin increases the number of reactive astrocytes causing Alzheimer diseases [40]. Here, EDN1 is linked to Alzheimer disease.