TFPIc23 induction of apoptosis in HUVECs. Quiescent HUVECs were stimulated with either 10 ng/mL bFGF (A) or complete serum (B) in the presence of 40 μM TFPIc23 or equal volume of PBS. After 24 or 48 hours, cells were fixed and sorted into sub-G₁, G₁, S, and G₂/M groups on the basis of propidium iodide incorporation.