P3H1 and osteogenesis imperfecta: A reduction in posttranslational proline hydroxylation was reported to favor overmodification of collagen chains and affect the stability of the collagen triple helix,(46) the assembly of collagen fibrils,(47) and could have an impact on mineralization of the bone matrix.(48, 49) Mutations in P3h1, one of the enzymes responsible for hydroxylation of proline residues in collagen chains, are responsible for some forms of osteogenesis imperfecta.(50) However, expression of P3h1 that might alter the hydroxylation of collagen was not significantly different in our model.