SELP and cancer: CD24 is another ligand for P-selectins expressed on platelets and endothelial cells that is modified with sLex, and aids in P-selectin-dependent rolling of breast and bladder cancers during metastasis to the lungs (Fig. 4).118 Sialylation of CD133 (another cell-surface molecule identified as a cancer stem-cell marker)119 is also strongly linked to invasion and metastasis.120 In 2019, Scott and Drake reported that breast cancers with high levels of sLex show affinity for E-selectins on endothelial cells, leading to extravasation at potential secondary sites (Fig. 4).121