Fig. 2.

Roles of the LPPs in regulating the dephosphorylation of extracellular lipid phosphates at the cell’s surface (ecto-activities) and internal substrates through the intracellular activities. LPPs dephosphorylate extracellular LPA and S1P. LPPs also have intracellular effects, which depend on their catalytic activities. These effects occur downstream of receptor stimulation and they regulate the activations of phospholipase D, ERK, and Ca²⁺-transients, The lipid targets of these intracellular activities are unknown.