Fig. 7.

 Effect of heat shock on MCF-7 cells. (A) MCF-7 cell clones (C14 and C20) were cultured with (off) or without (on) doxycycline and exposed to heat shock of 43°C for either 30 or 60 minutes. Cells were returned to 37°C and harvested 24 hours later for cell counts. Data are reported as percentage of control (±SEM). Significant differences in cell numbers at P < 0.05 (*), P < 0.01 (**), and P < 0.001 (***) compared with C14-on cells are indicated. n = 6 replicates for C14 cells; n = 3 for C20 cells. (B) MCF-7 clone C14 cells were cultured with (off) or without (on) doxycycline and exposed to heat shock of 43°C for 60 minutes (n = 3 replicates). Cells were returned to 37°C for 24 hours and stained with ethidium bromide and acridine orange. Percentage of viable, dead, and apoptotic cells are reported (±SEM). Significant differences between C14-on and C14-off cells at P < 0.05 (*), P < 0.01 (**), and P = 0.051 (†) are indicated