Figure 1.

Prodigiosin induces G₁ cell cycle arrest and increased expression of p21^CIP1 and 27^KIP1 in multiple human lung adenocarcinoma cell lines. (A) Prodigiosin at non-cytotoxic concentrations arrests cells in the G₁ phase. A549, CL1-5 and H23 cells were treated with prodigiosin (0–100 nM) for 24 h and then subjected to flow cytometry analysis for cell cycle distribution. It is clear that apoptoptic cells (sub-G₁ phases) were barely elicited by prodigiosin at the concentrations used. An evident increase in the % of cells in the G₁ phase was observed, along with a concomitant decrease in cells in the S phase. (B) Increase in the levels of p21^CIP1 and p27^KIP1 in prodigiosin-treated cells. A549, CL1-5 and H23 cells were treated with prodigiosin (0∼100 nM) for 24 h and then subjected to immunoblotting analysis for the protein levels of p21^CIP1 and p27^KIP1. Human β-tubulin was used as the loading control. Shown here is a representative blot from at least three independent experiments. PG, prodigiosin.