Effect of (+)-vitisin A (Vt-A) on pit-forming activity in RANKL stimulated RAW264.7 cells.

(A) Cells cultured on bone slices were stimulated with RANKL for 8 days by concurrent addition of Vt-A. (B) Vt-A was added at 5 days after RANKL stimulation and differentiated for further 3 days. After removing the cells, the slices were stained with Mayer's haematoxylin to identify resorption pits. The resorption area was observed under a light microscope and analyzed by Image-Pro Plus. Data represent the mean ± SEM of three to five independent experiments. *p<0.05 and **p <0.01, different from values after treatment with RANKL alone.