β-catenin heterozygous knockout mice do not respond to loading. Data represent mean ± SD for bone formation rate/bone surface (BFR/BS), bone formation rate/bone volume (BFR/BV), bone formation rate/total volume (BRF/TV), single labeled surface per bone perimeter (sL.S/B.Pm), and double labeled surface per bone perimeter (dL.S/B.Pm) in the endocortical and periosteal region. Group size n=5 for male controls and HET cKO, n=4 for female controls and HET cKO. a = statistically significant different comparing male to female; b = statistically significantly different comparing control versus HET cKO; and c = statistically significant different between non loaded and loaded ulna. Statistical significance was determined using a two independent sample t-test (control and HET cKO) and matched paired t-test for left and right (load, non-loaded).