FIG. 3.
Combined effects of topo I and II trapping on DNMT1 adduct formation. HeLa cells (exponentially growing; 4 × 107 cells/ICM) were cultured for 24 h without or with aza-dC (5 μM), followed by 30 min of exposure to VP16 (10 μM) or CPT (50 μM) as indicated and subjected to the ICM assay. Increasing amounts of DNA (from 1 to 10 μg) were spotted on the membrane. (A) Two cultures were treated with either VP16 or CPT and probed with anti-DNMT1 antibody. (B) Three plates were treated with aza-dC alone or with aza-dC/VP16 and aza-dC/CPT as indicated. Increasing amounts of DNA were spotted and probed with anti-DNMT1 antibody. Panel C shows several controls where the blot was probed with anti-topo I antibody.