Notes: Promega's Casein Kinase II and DNA-Dependent Protein Kinase were used for in vitro phosphorylation of the SV40 large T antigen expressed either from Rabbit Reticulocyte Lysate or a large Tantigen-β-Gal fusion protein expressed in a rat hepatoma cell line. Lysates and cell extracts were assayed for DNA-dependent protein kinase activity with a peptide substrate. The ability of β-Gal-T antigen fusions (± phosphorylation) to bind to murine importin subunits was assessed by an ELISA system using the Anti-β-Galactosidase mAb. (0120)