Similar increases in Ank and Enpp1 expression by mouse osteoblasts by extracellular Pi have been previously noted (Rendenbach et al., 2014) and may, along with decreased local phosphatase expression, contribute to the accumulation of unmineralised osteoid observed in Fgf23-deficient mice, despite a marked hyperphosphatemia (Sitara et al., 2004). Here, FGF23 is linked to hyperphosphatemia.