Fig. 5.

Infection with T. gondii results in an oscillatory profile of ERK activation. Confluent HFF grown in 24-well plates were infected with T. gondii RH at an m.o.i. of 5:1 (A) or stimulated with 2 ng/ml of EGF (B) over a period of 36 h. Cells were processed for SDS-PAGE followed by immunoblotting using antibodies against phosphorylated ERK and total ERK as a loading control. The kinetic profile of ERK phosphorylation in infected cells shows an oscillatory pattern of activation in contrast to a rapid and sustained response induced by EGF during the first 24 h. At later time points, however, the response to growth factor stimulation returned to baseline while levels of phospho-ERK in T. gondii-infected cells remained elevated.