Modulation of integrins regulates cell cycle progression. A: 4T1, GFP-4T1, 4T1-α5, and 4T1-α6-shRNA1 cells were synchronized and stained with propidium iodide for cell-cycle analysis. Cells were arrested at G1/S stage for 4T1-α5 and 4T1-α6-shRNA1 (37 and 42) compared to controls (26 and 28), and have shorter S phase for 4T1α5 and 4T1 α6 shRNA(52, 49) compared to controls (65, 67). No significant changes in G2 phase were noted (4T1 α5:10, 4T1 α6-shRNA1;8, 4T1 control: 8, and 4T1 GFP: 7). B. RT-PCR data. RNA was isolated from all the four cell lines and RT-PCR was performed for E2F1, chk1, Cyclin E and CDK2. GAPDH control was used as a control.