Figure 7
The functional activity of Bcl-XL is more than ten times greater than Bcl-2 in increasing clonal survival after exposure to doxorubicin. A) Cells expressing Bcl-2 or Bcl-XL, as indicated, were exposed to 5 μM doxorubicin in estrogen free medium for 1 hour, then replated in drug free, estrogen replete medium and allowed to grow for 14 days. Surviving colonies were visualized by staining with crystal violet. B) The number of surviving clones was counted and the results expressed as the number of surviving clones corrected for expression level of the respective protein for each cell clone. The data shown on a logarithmic scale is from one experiment performed in triplicate and is representative of three independent experiments. Bars indicate standard error of the mean.