PF4 stimulation of aPC generation on the surface of TM-expressing cells. (A) aPC generation studies using TM-expressing or control K293 cells. Cells were incubated with increased concentration of PF4 followed by addition of PC (500nM) in the absence or presence of 2nM IIa. Data are mean ± SD of 3 experiments, each performed in duplicate. *P < .05 vs no added PF4. (B) Generation of aPC as in panel A, either untreated or treated with 1 U/mL of heparinase, chondroitinase, or both enzymes. Data are mean ± SD of 3 experiments, each performed in duplicate. *P < .02 vs control. (C) Generation of aPC using primary HAECs treated with either 2.5 U/mL of chondroitinase or buffer. Data are mean ± SD of 2 experiments performed on cells on passage P5 and P6, each done twice. *P < .01 vs buffer.