Magnesium-independent phospholipid phosphatase that catalyzes the dephosphorylation of a variety of glycerolipid and sphingolipid phosphate esters including phosphatidate/PA, lysophosphatidate/LPA, sphingosine 1-phosphate/S1P and ceramide 1-phosphate/C1P (PubMed:9705349, PubMed:9607309, PubMed:16467304). Has no apparent extracellular phosphatase activity and therefore most probably acts intracellularly (PubMed:16467304). Also acts on N-oleoyl ethanolamine phosphate/N-(9Z-octadecenoyl)-ethanolamine phosphate, a potential physiological compound (PubMed:9607309). Through dephosphorylation of these bioactive lipid mediators produces new bioactive compounds and may regulate signal transduction in different cellular processes (Probable). Indirectly regulates, for instance, cell cycle G1/S phase transition through its phospholipid phosphatase activity (By similarity). a 1,2-diacyl-sn-glycero-3-phosphate + H2O = a 1,2-diacyl-sn-glycerol + phosphate 1,2-dihexadecanoyl-sn-glycero-3-phosphate + H2O = 1,2-dihexadecanoyl-sn-glycerol + phosphate 1,2-di-(9Z-octadecenoyl)-sn-glycero-3-phosphate + H2O = 1,2-di-(9Z-octadecenoyl)-sn-glycerol + phosphate H2O + monoacyl-sn-glycero-3-phosphate = a monoacylglycerol + phosphate (9Z)-octadecenoyl-sn-glycero-3-phosphate + H2O = (9Z-octadecenoyl)-glycerol + phosphate H2O + sphing-4-enine 1-phosphate = phosphate + sphing-4-enine an N-acylsphing-4-enine 1-phosphate + H2O = an N-acylsphing-4-enine + phosphate H2O + N-(octanoyl)-sphing-4-enine-1-phosphate = N-octanoylsphing-4-enine + phosphate H2O + N-(9Z-octadecenoyl)-ethanolamine phosphate = N-(9Z-octadecenoyl) ethanolamine + phosphate Magnesium-independent phospholipid phosphatase (PubMed:9705349). Insensitive to N-ethylmaleimide (PubMed:9705349). Inhibited by sphingosine, zinc ions and modestly by propanolol (PubMed:9705349, PubMed:9607309). Lipid metabolism; phospholipid metabolism. Forms functional homodimers and homooligomers (PubMed:18215144). Can also form heterooligomers with PLPP1 and PLPP3 (PubMed:18215144). Found mainly in brain, pancreas and placenta. N-glycosylated. Belongs to the PA-phosphatase related phosphoesterase family.