Figure 7: RT-PCR analysis of cell cultures between stimulus conditions (from 10 min/day to 180 min/day) and static culture for 10 days (A). RNA was extracted from the cell cultures at 10 days after the addition of differentiation media. These extracts were subjected to RT-PCR analysis with Runx2, COL1, OCN, OPN, SMAD1, and GAPDH as the positive control. Expression levels (B) of COL-1 (a), Runx2 (b), OPN (c), and OCN (d) at 10 days were significantly higher in OSS stimulus conditions on cells than those in control. OSS groups exposed at 10, 30, 60, and 120 min/day were significantly different ( and ) among groups.