Fig. 4. Effect of RA on cell proliferation in MC3T3-E1 preosteoblasts on Ti surface. Proliferation of MC3T3-E1 cells on Ti discs treated with or without 14 µg/ml RA were confirmed via MTT assay. Cell proliferation in RA-treated preostoblasts on Ti discs increased (p<0.05). RA: rosmarinic acid, Ti: titanium. *p<0.05, compared to control.