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. Has no apparent extracellular phosphatase activity and therefore most probably acts intracellularly. Also acts on N-oleoyl ethanolamine phosphate/N-(9Z-octadecenoyl)-ethanolamine phosphate, a potential physiological compound. Through dephosphorylation of these bioactive lipid mediators produces new bioactive compounds and may regulate signal transduction in different cellular processes (By similarity). Indirectly regulates, for instance, cell cycle G1/S phase transition through its phospholipid phosphatase activity (PubMed:16467304). 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. Insensitive to N-ethylmaleimide. Lipid metabolism; phospholipid metabolism. Forms functional homodimers and homooligomers. Can also form heterooligomers with PLPP1 and PLPP3. Expressed in the brain. N-glycosylated. Belongs to the PA-phosphatase related phosphoesterase family.