Effects of a small cyclic RGD peptide (cyclic RGD) on HUVECs spread on vitronectin or fibronectin or plated on polyHEMA-coated surfaces. Peptide was added 3 hours after seeding of cells on matrix components or when cells were seeded on polyHEMA-coated surfaces. (A) Apoptosis was assessed by flow cytometry after annexin V and propidium iodide staining. Results of 1 of 2 experiments with similar results are shown. (B) Procaspase-8, procaspase-9, cleaved caspase-3, and PARP were detected by Western blotting. Erk1/2 was used as loading control. *Nonspecific detection of BSA. Results of 1 of at least 2 experiments with similar results are shown.