CALP2 TFA, a potent calmodulin (CaM) antagonist with a dissociation constant (Kd) of 7.9 µM, exhibits high affinity for the CaM EF-hand/Ca2+-binding site. This compound effectively inhibits CaM-dependent phosphodiesterase activity and elevates intracellular Ca2+ concentrations. Furthermore, it significantly hinders adhesion and degranulation, while also acting as a robust activator of alveolar macrophages [1] [2] [3] [4].