At the endoplasmic reticulum (ER) membrane, phosphatidylinositol (PI) is hydrolyzed, and has one of its acyl chains cleaved off, by a phospholipase A2 to form 1-acyl lysophosphatidylinositol (LPI). The phospholipases are either cytosolic phospholipase A2 alpha/beta/zeta (PLA2G4A/D/F) (Ghomashchi et al. 2010), group XVI phospholipase A2 (PLA2G16) (Duncan et al. 2008), or Phospholipase B-like 1 (PLBD1) (Xu et al. 2009). PLBD1 also acts as a phospholipase A2 but in addition has the propensity to hydrolyze the lysophospholipid formed in its initial reaction.