FGF23 and Alzheimer disease: We previously reported that the active form of FGF23 (intact FGF23) in AnkKI/KI mice, a model for AD CMD, was comparable but found an increased inactive form of FGF23 (C-terminal FGF23).10 Our data showed that there were no significant differences in intact FGF23 and C-terminal FGF23 levels between Cx43+/+ and Cx43KI/KI mice (Fig. 3c).