FIGURE 2.

Pu-27 induces phosphorylation of H₂AX (γH₂AX). U937 cells and ΔB-U937 cells treated with Pu-27 and were subjected to Western blot and FACS analysis. A, 3-day treatment of Pu-27 showed profound up-regulation of γH₂AX expression in U937 cells but almost no changes in dB-U937 cells. Relative expressions of TRF2 in U937 and ΔB-U937 cells were also shown. TRF2 expression is down-regulated in U937 cells and no changes in ΔB-U937 cells when treated with Pu-27 (consistent with RT-PCR data in Fig. 6). Bottom panel, relative expression presented in bar graphs. *, p < 0.05. B, by FACS analysis γH₂AX has shown continued to be highly expressed from days 1–3, and again there was no significant change in ΔB-U937 cells. Bottom panels, relative expression presented in bar graphs. *, p < 0.05.