The BMOp cells from loaded and unloaded bones were grown in culture. Total RNA was harvested at days 5, 7, 14, and 21 in culture and cell lysates collected at days 7, 14, and 21 in culture. A) Relative mRNA expression of the integrin subunits normalized to L19 of the unloaded BMOp cells as a percentage of that of loaded BMOp are displayed. Means ± SEM, of four independent BMOp cell pools at day 5, thirteen at day 7, six at day 14 and four at day 21. a p < 0.05, b p < 0.01, c p = 0.055. B) A representative immunoblot illustrates that expression of the β1 integrin subunit was significantly less than that in loaded BMOp cells after 7 days but not 14 or 21 days in culture. Relative signal intensities of the ratio of β1 integrin to actin were evaluated. Means ± SD, n = 3. a p < 0.05 vs. Loaded.