Figure 2

Alkaline Phosphatase Staining. The alkaline phosphatase positive staining colonies first appeared at the 1^st day's culture of control groups, and then progressively increased as the culture period passed, and attained a significant degree at the 7^th day's culture. When osteoblasts cultured with 10 mM concentration of caffeine, the appearance of alkaline phosphatase staining was likely affected a lot. In the presence of 10 mM caffeine, the viability of osteoblasts was decreased and the residual cells lost their reaction to alkaline phosphatase staining.