A bioactive sphingolipid; inhibits IL-4 production by 16% in PMA-stimulated EL4 T cells at 10 μM; cytotoxic to SK-BR-3 and MCF-7/Adr breast cancer cells (IC50s = 15.9 and 19.9 μM, respectively); increases maturation and stability of F508del-CFTR proteins, enhances cAMP-activated chloride secretion, and suppresses secretion of IL-8 in primary epithelial cells isolated from patients with cystic fibrosis