Caloxins are extracellular plasma membrane (PM) Ca2+ pump inhibitors. Caloxin 2A1 is a PM Ca2+ pump inhibitor selectively binding to an extracellular domain. It inhibits Ca2+-Mg2+-ATPase in human erythrocyte leaky ghosts. Caloxin 2A1 is active at an extracellular site, the peptide can simply be added exogenously to inhibit the plasma membrane calcium ATPase (PMCA). Related peptides: Caloxin 1A1 (cat# 62605) and Caloxin 3A1 (cat# 62606).