Figure 1. Treatment of NIH/3T3 cells with PDGF stimulates phosphorylation of p44/42 MAPK at Thr202/Tyr204, detected by the PathScan ® Phospho-p44/42 MAPK (Thr202/Tyr204) Sandwich ELISA Kit #7177, but has little effect on the total level of p44/42 MAPK detected by PathScan ® Total p44/42 MAPK (Erk1/2) Sandwich ELISA Kit. NIH/3T3 cells (80-90% confluent) were starved overnight and treated with 100 ng/mL PDGF for 5 minutes at 37ºC. The absorbance readings at 450 nm are shown in the top figure, while the corresponding western blots, using p44/42 MAPK (Erk1/2) Antibody #9102 (left panel) and Phospho-p44/42 MAPK (Erk1/2) (Thr202/Tyr204) (D13.14.4E) XP ® Rabbit mAb #4370 (right panel), are shown in the bottom figure.