Osteoclast and osteoblast precursors were obtained from bone marrow of WT and dnMAML mice. Osteoblast precursors were cultured in the presence of maintenance media, osteogenic (OG) media (maintenance media supplemented with β-glycerol phosphate, ascorbate, and dexamethasone), OG media were combined with conditioned media from WT or dnMAML osteoclasts, or OG media supplemented with BMP-6 as a positive control. After 15 days of differentiation, (A) ALP activity was determined using SensoLyte pNPP Alkaline Phosphatase Assay Kit, and (B) calcium deposits were quantified after alizarin red staining. Both ALP activity and alizarin red staining were significantly increased in all treatment groups compared to maintenance media (*P<0.05). Similarly, ALP activity and alizarin red staining were significantly increased when OG medium was supplemented with conditioned medium from both WT and dnMAML osteoclasts as well as with BMP-6 (†P<0.05). There was no significant difference between cells treated with WT and dnMAML conditioned media. (C) Osteoblast genes (ALP, OSX and RunX2) in 6-month dnMAML females were significantly increased as measured by qRT-PCR. Values represented are Mean ± S.D and P value was calculated using Student t-test (*P<0.05, †P<0.05).