Fig. 4.

(A) Effects of crude saponin fraction on collagen-induced phosphorylation of mitogen-activated protein kinases. Washed platelets (3 × 10⁸/mL) were preincubated for 2 min with vehicle or crude saponin fraction at the indicated concentration. The platelets were then stimulated with 2.5 μg/mL collagen for 5 min at 37°C. After terminating the reactions, total cell proteins were extracted. The proteins were separated by sodium dodecyl sulfate–polyacrylamide gel electrophoresis and transferred onto nitrocellulose membranes. The membranes were then probed with antibodies against phospho-p44/42, p44/42, phospho-p38, p38, phospho-SAPK/JNK, and SAPK/JNK (JNK). Antibody binding was visualized by chemiluminescence. All immunoblots are representative of three or four independent experiments. (B) The bar graph shows that the density of specific band was measured and the data are presented as the mean +/− standard deviation of three or four independent trials. * p < 0.05, ** p < 0.005, *** p < 0.001 versus vehicle control. Coll, collagen; ERK, extracellular signal-regulated protein kinase; JNK, c-Jun N-terminal kinase; MAPK, mitogen-activated protein kinase.