Glycerophosphoinositol 4-phosphate (GroPI(4)P) is a synthetic, purified PI(4)P without acyl chains at the 1- and 2-positions of the glycerol. Phosphoinositides (PIPns) are minor components of cellular membranes but are integral signaling molecules for cellular communication. Phosphatidylinositol 4-phosphate (PI(4)P) is the biosynthetic precursor to PI(4,5)P2 and has an important roles in regulating sphingomyelin and glycosphingolipid metabolism and membrane trafficking at the exit of the Golgi complex.