Has glycerophosphoinositol inositolphosphodiesterase activity and specifically hydrolyzes glycerophosphoinositol, with no activity for other substrates such as glycerophosphoinositol 4-phosphate, glycerophosphocholine, glycerophosphoethanolamine, and glycerophosphoserine. Accelerates the program of osteoblast differentiation and growth. May play a role in remodeling of the actin cytoskeleton (By similarity). H2O + sn-glycero-3-phospho-1D-myo-inositol = 1D-myo-inositol 1-phosphate + glycerol + H(+) Colocalizes with the actin cytoskeleton. Belongs to the glycerophosphoryl diester phosphodiesterase family. The catalytic domain of GDPD2 is oriented extracellularly; Glycerophosphoinositol is hydrolyzed in the medium of cells overexpressing Gdpd2, whereas intracellular levels of glycerophosphoinositol is not affected.