Figure 2. Effect of TNF- on apoptosis in periosteal fibroblasts, osteoblasts, and osteocytes under static conditions. TNF- at 10 ng/mL for 16 hrs increased caspase-3/7 activity in osteocytes and osteoblasts by more than two-fold, but not in periosteal fibroblasts. Values, obtained from 3 (periosteal fibroblast) or 4 (osteoblast and osteocyte) separate experiments, are expressed as mean ± SEM of TNF--treated-over-control ratios (± TNF- at 10 ng/mL). Dashed line, ± TNF- = 1 (no effect). PF, periosteal fibroblasts; OB, osteoblasts; OCY, osteocytes. *Significant effect of TNF- , p < 0.05.