FGFR1 and chronic kidney disease: Plasma FGF23 levels were significantly elevated in CKD mice: Fgfr1–3flox/flox, control (212.0 ± 34.2 pg/mL, n = 5) vs CKD (19531.1 ± 9232.3 pg/mL, n = 5), P < 0.001; αKlothoflox/flox, control (182.0 ± 43.6 pg/mL, n = 8) vs CKD (19949.4 ± 14188.7 pg/mL,n = 6), P < 0.01; Fgfr1–4flox/flox, control (232.0 ± 82.7 pg/mL, n = 8) vs CKD (37005.2 ± 15197.4 pg/mL, n = 8), P < 0.001, corresponding to the levels of plasma phosphate.