In the results of in vivo experiments using OVX- or aging-induced osteoporosis model, osteoblast-specific knockout of HIF-1α (Hif1afl/fl;Col1a1-Cre mice) showed no differences in osteoclast differentiation and activation compared to control, Hif1afl/fl mice, although Hif1a cKO did show a significant increase in BMD and bone parameters (Fig. 6). Here, COL1A1 is linked to osteoporosis.