Skeletal muscles attach to the skeleton via tendons, and skeletal movement requires a tight physical interaction between skeletal muscles and tendon cells. Myotubes are the skeletal muscle precursors, and nascent myotubes are guided to tendon cells through largely unknown mechanisms. In a genetic screen for regulators of embryonic body wall muscle development, we identified the Out-of-step (ofs) phenotype in which nascent myotubes failed to extend toward tendon cells in a synchronized manner. The ofs allele mapped to a previously uncharacterized serine/threonine kinase that is orthologous to mammalian Vaccinia Related Kinase (VRK), and neither VRK nor Ofs have been studied in the context of myogenesis. Using LifeAct.GFP, we found that ofs myotubes failed to extend filopodia during pathfinding. The leading edges of ofs myotubes initiate outgrowth but are unable to reach and attach to tendon cells. By RNA-seq, we found that Notch target genes in the Enhancer of Split Complex [E(Spl)-C] are enriched in ofs embryos. We are testing the hypothesis that contact dependent Notch signals inhibit myotube outgrowth, and that Ofs modulates the intracellular response to Notch. This study is the first to identify a protein kinase that directs myotube pathfinding, and will provide essential insights into the mechanisms by which filopodia probe the extracellular environment during cell migration.