Confirmation of inhibitors using the M13 DNA synthesis assay. Full-length ds DNA products labeled with [α-32P]dCTP were synthesized from the M13 DNA primer/template in the presence of the vaccinia triad (A20, D4, E9) and examined on a non-denaturing gel. The ability of each polymerase and processivity inhibitor to block the M13 DNA synthesis was examined by adding increasing concentrations (100 nM, 1 μM, 10 μM, 100 μM and 1 mM) of each compound: NSC 69343, lanes 3-7; NSC 55636, lanes 8-12; NSC 123526, lanes 13-17; NSC 124808, lanes 18-22. Lane 1 shows the position of the full-length ds M13 DNA marker (arrow) as detected by cybergold. Lane 2 is the control reaction containing DMSO, the solvent for each of the compounds. The position of greater than unit length products are indicated by brackets.