Phosphorylated-focal adhesion kinase expression in circulating tumor cells and co-expression of vascular endothelial growth factor/vascular endothelial growth factor receptor or vascular endothelial growth factor/hypoxia-inducible factor-1α in circulating tumor cells of patients with breast cancer. A (I): Representative image of a cytospin double stained with polyclonal pancytokeratin (red) and (monoclonal) pFAK (green) antibodies. A (II): Quantification of pFAK and CK co-expression in CTCs of 12 patients with metastatic disease. All the examined patients (100%) presented CTCs in their blood, while 92% also presented double positive cells (pFAK+CK+). B: Representative confocal laser scanning micrographs of CTCs cytospins after negative immunomagnetic separation in 10 patients with metastatic breast cancer. Cells cytospins were double stained with VEGF and either (I) VEGFR2 or (II) HIF-1α antibodies, respectively. C: Representative image of a cytospin, triple stained with monoclonal pancytokeratin (A45-B/B3) (green) and VEGF antibodies (blue) along with either (I) VEGFR2 or (II) HIF-1α (B) (red) polyclonal antibodies (red).