Casein kinase 2-interacting protein 1 (CKIP-1) plays a role in the regulation of the actin cytoskeleton through its interactions with actin capping protein (CP). CKIP-1 targets CK2 to the plasma membrane thereby serving as an adapter to facilitate the phosphorylation of CP by protein kinase 2 (CK2). CKIP-1 inhibits tumor cell growth by inhibiting AKT-mediated cell-survival. CKIP-1 is involved in PI3K-regulated muscle differentiation, the regulation of AP-1 activity and the promotion of apoptosis induced by tumor necrosis factor TNF.