Modulation of alkaline phosphatase and osteocalcin release in OA Ob by inactivating leptin or leptin signaling. OA Ob were treated with siRNA for either leptin or OB-Rb or a scrambled RNA as described in Material and methods. Cells were then used to determine alkaline phosphatase activity and osteocalcin release. A) Results of alkaline phosphatase activity in response to leptin or OB-Rb siRNA treatments. B) Results of osteocalcin release in response to leptin or OB-Rb siRNA treatments. C) Leptin expression in response to siRNA. D) OB-Rb expression in response to siRNA. Results are the mean ± SEM of n = 6 OA Ob preparations.