Figure 1.

(A) Twist1 expression, normalized to the housekeeper Rplp2, was significantly increased in osteocyte-enriched bone tissue lysates from 10-wk-old female WT C57Bl/6J mice that were injected with a single dose of 25 mg/kg sclerostin antibody (Scl-Ab), then sacrificed 2 days later. The same procedure using Dkk1 antibody (25 mg/kg) did not change Twist1 expression; n = 4/group, * p < 0.05. (B) Representative micrographs of β-galactosidase-reacted femora from Twist1^f/f mice that also carried the Rosa26-LacZ Cre reporter line. Qualitatively, negligible lacZ staining is apparent in the Cre-negative mice, but the mice positive for ^10kbDmp1-Cre exhibit a strong reaction in the bone tissue, indicating recombination activity of the Cre transgene. (C) Top: schematic showing the floxed Twist1 locus (2 exons) and the location within exon 1 of the forward and reverse primers (arrows) used to probe for the intact floxed allele in genomic DNA from cortical bone. Bottom: ratio of intact Twist1 sequence (target) to Apolipoprotein B sequence (control), in Cre-positive and Cre-negative mice; n = 8–9/group, * p < 0.05.