Structure and function of muscle cells dictate cell behavior. The muscle cytoskeleton provides structure to the cell and both generates and transduces force during muscle contraction. Although seemingly static, the cytoskeleton is actually a very dynamic framework containing numerous signaling molecules that regulate muscle growth and contractility. Because of these properties, it has been proposed that the muscle cytoskeleton is a signaling nexus that integrates cellular cues and generates responses to direct cell behavior such as growth and remodeling. We have focused our studies on two families of cytoskeletal proteins—the cysteine rich proteins (CRPs) and the actinin LIM protein (ALP)/Enigma proteins—that both display dynamic behavior and the capacity to participate in critical signaling pathways. In our current research, we are using the C. elegans model system to elucidate the molecular function of ALP/Enigma proteins (Figure 1). We use another genetic model system, the fruit fly Drosophila melanogaster, for our studies of the CRP family. Figure 2 shows the subcellular distribution of Mlp84B, a Drosophila CRP, in a developing embryo. The protein is enriched at the ends of the muscles where they attach to each other, to the tendon cells, and at the z-line. A small fraction of Mlp84B is also in muscle nuclei, suggesting that the protein may shuttle between these two compartments.