Tyrosine-protein kinase which is required during embryogenesis for formation of the actin cable in leading edge cells of the dorsal epidermis and for the timely progression of dorsal closure. May play a role in regulation of adherens junctions and cell adhesion through phosphorylation of the beta-catenin arm. ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] At stages 11-12 of embryogenesis, localizes to adherens junctions in epidermal cells. At stages 13-14, is no longer detected in the epidermal cell junctions which border with the amnioserosa. Expressed in a subset of cells in the embryonic central nervous system (CNS) (PubMed:16831834). In the embryo, expressed in leading edge cells of the dorsal epidermis (at protein level) (PubMed:16831834). Expressed in many tissues during embryonic development, some expression is transient and absent from most of nervous system (PubMed:1898762). In the embryo, strong expression in the leading edge cells from late stage 13 and throughout dorsal closure to the end of stage 15 (PubMed:16831834). In the embryonic CNS, expressed in the midline glia from stage 13, and by stage 16 expressed in a segmentally repeated subset of cells and in the dMP2 neurons (PubMed:16831834). Larvae exhibit expression in neural tissues and graded expression in all imaginal disks (PubMed:1898762). Pupal expression is seen in muscles and varies during development (PubMed:1898762). Expression in adults is strong in the retina and present in ovaries, no expression is present in the adult brain (PubMed:1898762). Expressed during all stages of development. 53% of mutants die during embryogenesis with the remainder dying during larval and pupal development. In embryos the rate of dorsal closure is reduced and complete closure is delayed until after stage 16. During dorsal closure, filopodia are normal but the actomyosin cable is reduced and the leading edge cells have an irregular morphology. After dorsal closure, a very small percentage of embryos display a small anterior hole in their cuticle. Reduced phosphorylation of arm. Belongs to the protein kinase superfamily. Tyr protein kinase family. Fes/fps subfamily.