The effects of inhibitors on tensile strain-induced expression of TIMP-1 mRNA in MC3T3-E1 cells. Cells were seeded at a density of 2 × 105 cells/well on Flex I culture plates and were cultured in α-MEM medium supplemented with 10% FBS for 24 h. They were then cultured in medium containing cycloheximide (10 μM), indomethacin (10 μM), genistein (20 μM), PD098059 (10 μM), or vehicle (control) for 30 min. The cells were cultured with (+) or without (-) loading with tensile strain at 18% elongation at 6 cycles/min for 24 h. Total RNA was isolated, and TIMP-1 and GAPDH mRNA levels were determined by RT-PCR. (A) Agarose gel electrophoresis of the TIMP-1 and GAPDH RT-PCR products. (B) TIMP-1 mRNA levels normalized to GAPDH. The results shown are means ± SD of five independent experiments. **Indicates a significant difference from stress (+) culture as determined by Student's t test (P < 0.01).