Figure 5.

Peptidic cyclin/cdk2 antagonists kill cells with deregulated E2F. Rat-1a fibroblasts stably transfected with a human E2F1 cDNA under the control of a zinc-inducible promoter (Rat-1a1093E2F1) were treated with the indicated peptides in the presence or absence of zinc. (A) Cell viability measured by MTS assay. (B) Cell-cycle distribution, measured by fluorescence-activated cell sorting after staining with propidium iodide (x axis) and FITC-conjugated anti-BrdUrd (y axis) of Rat-1a1093E2F1 cells in the presence (Upper) or absence (Lower) of zinc. Cells were treated with Tat-LDL (Left) or Tat-Umt (Right). Cells in G₂/M are shown in blue and cells in S phase undergoing active DNA replication (as measured by BrdUrd incorporation) are shown in green.