Figure 4.

The over-expression of the β2 subunit of proteasome increases the sensitivity to camptothecin. Cells expressing the β2 subunit and cells containing the pcDNA6/myc vector (control cells) were seeded at the density of 3 × 10² per plate. After 24 hours, cells were treated for one hour with camptothecin at the following concentrations: 10 μM, 20 μM, 40 μM, and 80 μM. After 7 days, the clones were stained with crystal violet and were counted.