Fig. 4. Effect of transient expression of wild-type and mutant Nek8 in cultured cells. (Top) Images of Cos7 cells stained with anti-HA monoclonal antibody and DAPI after transfection with (A) wild-type, (B) jck or (C) kinase-deficient Nek8. Transfection with the mutant Nek8 kinases results in enlarged, multinucleated cells. (Bottom) Images of MDCK cells stained with anti-HA monoclonal antibody, phalloidin and DAPI after transfection with (A) wild-type, (B) jck or (C) kinase-deficient Nek8. Staining with phalloidin alone is shown in A', B' and C'. The Nek8 protein is expressed predominantly in the cytoplasm, and actin stress fibers are reduced in cells that express the mutant Nek8 kinases.