Expression of FGF-23 mRNA and protein in erythroblasts. (A-B) FGF-23 mRNA in sorted CD45⁺ or CD45⁻ BM cells at 3 hours after single-dose G-CSF (A) or isoproterenol (B) (n = 3). (C) FGF-23 mRNA in sorted CD45⁺ BM cells or CD45⁻Ter119⁺CD71⁺ erythroblasts at 3 hours after single-dose G-CSF or isoproterenol (n = 3). (D-E) iFGF-23 (D) and cFGF-23 (E) protein levels in cell lysates of sorted CD45⁻Ter119⁺CD71⁺ erythroblasts at 2 hours after single-dose G-CSF or 1 hour after single-dose isoproterenol (n = 3). (F) iFGF-23 protein from the human erythroblast cell line HUDEP-2 after 4 hours of culture under the indicated oxygen conditions in the culture supernatants (n = 4-5). Combined data of at least 3 independent experiments are shown. Data are means ± SEM. *P < .05; **P < .01; ***P < .001 (ANOVA, Student t test, and Mann-Whitney U test). Ebls, erythroblasts.