SELP and neoplasm: Taken together, we conclude that CD24high bladder cancer cells are protected in organoids from CD24-induced apoptosis as urothelial cells express the CD24-ligand P-selectin at low levels, while at the same time elevated soluble P-selectin in the serum of bladder cancer patients prevents CD24 cross-linking on the tumor cells, and at the same time apoptosis of CD24high cells in tumor tissues.