We recently reported that the pharmacological inhibition of calcineurin (Cn) by low
concentrations of cyclosporin A increases osteoblast differentiation in vitro and bone mass in
vivo. To determine whether Cn exerts direct actions in osteoblasts, we generated mice
lacking Cnb1 (Cn regulatory subunit) in osteoblasts (ΔCnb1 OB) using Cre-mediated
recombination methods. Transgenic mice expressing Cre recombinase, driven by the
human osteocalcin promoter, were crossed with homozygous mice that express loxP …