Molecular mechanisms by which A11 inhibits tumor metastasis. (A-B) Effect of A11 on the adhesion of tumor cells to platelets in vitro. (A) The adhesion of LLCs to activated platelets as observed under fluorescence microscope. (B) The quantitative analysis of adhesion of LLC with activated platelet in the presence of various concentration of A11, as measurements of fluorescent intensity under a fluorescence plate reader. The experiment was repeated 3 times and each concentration had 4 wells. (C) Effect of A11 on the adhesion of platelets to HUVECs in vitro. The extent of adhesion was expressed as the percentage of control platelets adhering without preincubation with A11 or control scFv (13CG2). The experiment was repeated 3 times and each concentration had 4 wells. (D-E) Effect of A11 on platelet-mediated tumor cell adhesion to endothelial cell in vitro. B16 melanoma cells adhesion to HUVECs was performed as described in “Assay of tumor cells adhesion to endothelial cells.” (D) The adhesion efficiency of B16 tumor cell was observed under a fluorescence microscope. (E) Quantitative result of adhesion of B16 melanoma cells with HUVECs. (F) Effect of A11 on the destruction of already formed tumor platelet aggregates. Data and SD are given for 3 separate experiments at 0.5 μM reagent in which each time point represents 5 measurements.