Figure 3.

Negative regulation of cell proliferation by p33ING1b or p33ING2. RKO or RKO E6 cells were transfected with empty control, p33ING1b, or p33ING2 expression vector. (A) Colony-formation assay. After 2 weeks of G418 selection, colonies were fixed, stained with crystal violet, and counted. Data represent the means ± SD. Statistical analysis was carried out with the Student's t test. (B) Induction of apoptosis by p33ING1b or p33ING2 was analyzed. Data represent the means ± SD of three independent experiments. Statistical analysis was carried out with the Student's t test. (C) Cell-cycle regulation by p33ING1b or p33ING2 was analyzed by flow cytometry. Cell-cycle profiles (G₀/G₁, S, and G₂/M) were calculated with the modfit program.