SPHK1 and neoplasm: SK1 is a tumour-associated enzyme: high levels of SK1 expression have been shown in various human tumours such as blood, brain, breast, colon, lung, ovary, stomach, uterus, kidney, prostate, rectum and small intestine [11–16] where they enhance tumour neovascularisation [17] and metastatic potential by promoting motility and invasion of cancer cells [18].