These authors identified the murine homolog of inositol polyphosphate 4-phosphatase type IIα (Inpp4bα) as a regulator of osteoclastogenesis,. Expression of Inpp4bα was detected from early osteoclast differentiation to activation stage. Targeted expression of native Inpp4bα ex vivo repressed whereas phosphatase-inactive Inpp4bα stimulated osteoclast differentiation. Mice deficient in Inpp4b displayed increased osteoclast differentiation rate and potential resulting in decreased bone mass and osteoporosis. Finally, INPP4B in humans was identified as a susceptibility locus for osteoporosis.