Figure 1. Effects of TNF- induction time (A) and TNF- dose (B) on caspase-3/7 activity in osteoblasts under static conditions. (A) The earliest time point at which apoptosis could be detected was after 16 hrs of 10 ng/mL TNF- treatment. (B) Maximal induction of apoptosis was achieved by 10 ng/mL TNF-. Higher and lower concentrations of TNF- resulted in less induction of apoptosis. Values, obtained from 3 wells of 1 experiment, are expressed as mean ± SEM of TNF--treated-over-control ratios (± TNF- at 10 ng/mL [A]; ± TNF- at 5, 10, 25, 50, 100 ng/mL [B]). Dashed line, ± TNF- = 1 (no effect). *Significant effect of TNF-, p < 0.05.