text: Lysophosphatidylinositol (LPI, lysoPI), or -α-lysophosphatidylinositol, is an endogenous lysophospholipid and endocannabinoid neurotransmitter. LPI, along with its 2-arachidonoyl- derivative, 2-arachidonoyl lysophosphatidylinositol (2-ALPI), have been proposed as the endogenous ligands of GPR55.