Fig. 5. FRK-1 kinase activity is not required for enclosure and elongation. (A) In vitro assays demonstrate the autophosphorylation activity of FRK-1, which is eliminated in the FRK-1(D308R) mutant. The enclosure and elongation defects of mDf7 homozygous embryos (B) are rescued by expression of the kinase-dead form of FRK-1 (C). The rescued embryos express the seam-cell-specific marker, NE2-1B4 (C), as is seen with rescue by wild-type FRK-1.