The neuromuscular junction (NMJ) is a peripheral cholinergic synapse that conveys signals from motor neurons to muscle cells (Sanes and Lichtman, 1999; Sanes and Lichtman, 2001). The formation of the NMJ requires communication between motoneurons and muscle fibers. Three molecules are essential for NMJ formation: agrin, MuSK, and rapsyn. MuSK appears to be involved in every aspect of NMJ development and maintenance. The paper reviews agrin-MuSK cascades and its potential cross talk with Wnt signaling pathways.