Fibrinogen is a heterodimeric protein that can be cleaved by thrombin. Fibrinogen is a potential marker for cardiovascular disease and plays an important role in metabolism. Its absence can cause fibrinogenemia.

Confluent MVECs were serum starved for 16 h and incubated with one of the following: Fibrinogen (2 or 4 mg/ml), Fibrinogen (4 mg/ml) with antibody against ICAM-1 (50 μM), Fibrinogen (4 mg/ml) with antibodies against α5 and β1, or β3 integrins (50 μM each), or Fibrinogen (4 mg/ml) with MEK inhibitors PD98059 or U0126 (50 μM each) at 37°C for 30 min. Fibrinogen induced a distinct dose-dependent increase of ERK phosphorylation that was significantly decreased by the presence of MEK inhibitors, PD98059 or U0126. Treatment of ECs with PD98059 (0.44 ± 0.03 FIU/cell, n = 4) or U0126 (0.40 ± 0.02 FIU/cell, n = 4), did not alter ERK phosphorylation in ECs compared to that in the control group (0.50 ± 0.05 FIU/cell, n = 4). [1]