Mutual Up-Regulation of Thyroid Hormone and Parathyroid Hormone Receptors in Rat Osteoblastic Osteosarcoma 17/2.8 Cells* * This work was supported by Buehler Research Grant 1999 from the Buehler Center on Aging, McGaw Medical Center, Northwestern University (to G.-G.D.) and a research grant from the Department of the Army, DAMD 17-96-1-6304 (to P.H.S. and L.D.M.). A portion of these studies was presented at the Second Joint Meeting of The American Society for Bone and Mineral Research, 1998, San Francisco, CA, and the 10th International Congress of Endocrinology, 1996, San Francisco, CA.