Activation of p38 MAPK in HUVECs stimulated with thrombin: a dose response.

(A) HUVECs were stimulated with various concentrations (0.5, 2, 4, 8 U/mL) of thrombin for 5 minutes, and then using specific antibody, native p38 (lane 1) or phosphorylated p38 MAPKs (lane 2) were detected in HUVEC cell lysates, and phosphorylation of ATF-2 was tested in vitro (lane 3). (B) Schematic representation of the thrombin dose response on p38 phosphorylation (fold activation relative to unstimulated cells is indicated, **P < .01, *P < .05, n = 3). The phospho-p38 index was calculated for each condition as follows: phospho-p38 concentration/native p38 concentration, each concentration being determined by comparing each band density using a gel analyzer.