Priming of platelet responses to collagen by TPO is mediated through PI 3-kinase.

(A) Platelets were preincubated with (i) 50 μmol/L LY294002 (LY) or (ii) 100 nmol/L wortmannin (Wt) given either 3 minutes before or 2 minutes after TPO (50 ng/mL). In both sets of experimental paradigms, platelets were left for 5 minutes after the addition of TPO before stimulation by collagen (1 μg/mL). (B) Platelets were preincubated 3 minutes with TPO (100 ng/mL) and/or apyrase (1 U/mL) as indicated and then stimulated by collagen. Results are shown from 1 experiment that is representative of at least 5.