Background: Adducin is a membrane skeletal protein that binds to actin filaments (F-actin) and promotes the association of spectrin with F-actin to form a spectrin-actin meshwork beneath plasma membranes (1-2). Adducin is a heterodimeric protein that consists of related subunits, ? and ?, or ? and ? subunits (3). Adducin binds with high affinity to Ca(2+)/calmodulin and is a substrate for protein kinase C (PKC), and protein kinase A (PKA) (4). PKA specifically phosphorylates Ser408, Ser436, and Ser481 located in the neck domain of alpha Adducin. Phosphorylation of Adducin alpha by Rho-kinase at Thr445 and Thr480 enhances the F-actin-binding activity of Adducin alpha (5).