Fig. 1.

S1P is a regulator of many processes important for cancer and inflammatory disorders. Many stimuli increase S1P by increasing the activity of SphK1 and SphK2. S1P secreted from cells activates specific S1P receptors, either on the same cell or on neighboring cells, and downstream signaling mediates disease progression. S1P also has direct intracellular targets that are likely to be important.