Figure 2

Occupancy of Sp3 at GC2 of the topoisomerase IIα promoter increases after doxorubicin treatment. ChIP analysis was carried out using MDA MB 231 breast cancer cells. Cells were exposed to a single dose of doxorubicin (5 μM) for 1 hour and cell extracts were taken at 0 hr (control), 2 hr and 24 hr after initial exposure. Values were calculated as in the legend for Figure 1 and represent the average and standard error of the fold enrichment in three experiments carried out in triplicate. The corresponding gel photograph (inset) shows PCR products from real time PCR of Sp1 or Sp3 binding to GC2 in unexposed (0 hr) and exposed (2 h and 24 h) cells. I indicates input control. Results are expressed as ± SEM where n = 9, *** p < 0.001, ** p < 0.01, and * p < 0.05.