(A) Cells stained with propidium iodide and analyzed by flow cytometry revealed that WA induces a dosedependent G2/M cell cycle arrest with an optimal range of such as response at 24h. Maximal induction of arrest above baseline was observed at 0.75µM, 1.5µM, and 0.5µM for U87, U251, and GL26 cells, respectively. Adjacent histograms display representative examples of these peak values in each cell line. (B) G2/M arrest was confirmed by Western blotting for cyclin B1. At 24h, U87 and U251 cells demonstrated dose-dependent induction of cyclin B1 with highest levels at 1uM and 2.5µM, respectively