UASt regulatory sequences drive expression of a dominant-negative form of sax; encodes a truncated form of the protein that lacks the entire kinase domain.
Expression of saxDN.UAS.cVa under the control of Scer\GAL4btl.PS results in tracheal defects in the embryo; occasional loss of ganglionic or dorsal branches and misdirected dorsal branches that cross segment boundaries are seen.