Effects of compounds 3a and 4a on cell cycle distribution. MCF-7aro cells were treated with 3a and 4a at 1 and 25 μM for 24 hr and subjected to flow cytometric analysis after PI staining. Compounds 3a and 4a induced cell cycle arrest in G0/G1 phase. Histograms were analysed with FlowJo Software (Tree Star, Inc). Data are representative of three independent experiments performed in triplicate.