Fig. 2.
Expression of active MPO in K562 cells increases the level of etoposide-stabilized TOP2-DNA covalent complexes. (A) Comparison of MPO activity (left) and MPO immunofluorescence (right) in K562 cells, two MPO-expressing K562-derived cell lines (K562MPO line4 K562MPO line5), and in NB4 cells. (B) K562 and K562MPO cell lines were incubated with 10 or 100 µM Etoposide or a vehicle control for 1 hour. Etoposide-stabilized TOP2-DNA complexes were quantified by TARDIS analysis using antibodies specific for TOP2A or TOP2B as described for Fig. 1. Numbers of replicates are indicated. *P < 0.05; **P < 0.01; ***P < 0.001.