DOR overexpression exacerbates T3-induced increase in ALP activity. A: expression of DOR in MC3T3-E1 cells transduced with murine leukemia virus-β-galactosidase (MLV-β-Gal) or MLV-DOR as determined by Western blot using whole cell lysates. B: MLV-β-Gal- and MLV-DOR-overexpressing MC3T3-E1 cells were treated with T3 (0.1, 1, 3, and 10 ng/ml), and ALP activity was determined 72 h after treatment. Values are presented as %vehicle-treated MLV-β-Gal ± SE (n = 5–8). Basal ALP activity values of MLV-β-Gal (1.48 mU/mg protein ± 0.11) and DOR-overexpressing cells (2.52 mU/mg protein ± 0.18). Data were analyzed by 2-way ANOVA, and a significant interaction was observed between gene and treatment. AP < 0.05 vs. vehicle-treated control; BP < 0.05 vs. MLV-β-Gal at corresponding dose.