SELE and neoplasm: The ESTA aptamer recognized E-selectin with nanomolar affinity (Kd = 47 nM) on cultured endothelial cells and tumor-associated vasculature in human breast, ovarian, and skin carcinomas, and potently inhibited adhesion of a human promyelomonocytic cell line expressing sLex, a natural ligand for E-selectin, to E-selectin-expressing endothelial cells.