Mg(2+)-dependent phosphatase that catalyzes the hydrolysis of the 1-position phosphate from inositol 1,4-bisphosphate and inositol 1,3,4-trisphosphate and participates in inositol phosphate metabolism. 1D-myo-inositol 1,4-bisphosphate + H2O = 1D-myo-inositol 4-phosphate + phosphate 1D-myo-inositol 1,3,4-trisphosphate + H2O = 1D-myo-inositol 3,4-bisphosphate + phosphate Inhibited by Li(+). Signal transduction; phosphatidylinositol signaling pathway. Monomer. Ubiquitously expressed, with highest levels in pancreas and kidney. Belongs to the inositol monophosphatase superfamily.