FIGURE 1.

MN1 mRNA transcripts are induced by 1,25(OH)₂D₃ and by osteoblastic cell differentiation. MC3T3-E1 cells (A) or primary calvarial osteoblasts (B) were maintained at the proliferating stage or differentiated for 2 weeks as described under “Experimental Procedures.” Proliferating or differentiating cells were treated with 10 nm 1,25(OH)₂D₃ for the indicated times, and the expression of MN1, 24-hydroxylase, VDR, or 18 S RNA was examined by Northern blot analysis. C, primary osteoblasts were differentiated for the indicated times, and the expression of MN1 or 18 S RNA was examined by Northern blot analysis. D, total RNA was extracted from indicated tissues of 6-week-old wild-type mice, and the expression of MN1 was determined by Northern blot analysis. Ethidium bromide staining of 18 S/28 S ribosomal RNA was used to normalize loading differences.