SDF-1β mRNA and protein levels in Tet-Off-SDF-1β BMSCs are significantly increased relative to controls, which enhances BMSC osteogenic differentiation in vitro. (A) Normalized SDF-1β mRNA, (B) intracellular SDF-1β protein, and (C) extracellular SDF-1β protein levels. Insets show normalized SDF-1α mRNA and protein levels, respectively controls (24 h, ± 100 ng/ml Dox). (D) Representative Alizarin Red S (ARS)-stained wells (21 days, ± 100 ng/ml Dox). (E) Colorimetric quantification of extracted ARS at 570 nm. Tet-Off-SDF-1β or Tet-Off-EV BMSCs (± Dox) (***p <0.0001 Tet-Off-SDF-1β (−Dox) vs. Tet-Off-SDF-1β (+Dox) or Tet-Off-EV (±Dox), n = 3 per group).