W-7 is a selective calmodulin antagonist. W-7 inhibits the Ca2+-calmodulin-dependent phosphodiesterase and myosin light chain kinase with IC50 values of 28 µM and 51 µM, respectively. W-7 induces apoptosis and has antitumor and vascular relaxing activity. W-7 is a blocker of Kv4.3 and can be used for research of arrhythmias[1][2][3][4][5][6].