Effect of D18 and quinacrine treatment on ERK pathway in GT1 cells. Infected and uninfected GT1 cells were treated with Fab D18 (50 nM) or quinacrine (1 μM) for 6 days; approximately 20 μg of total proteins were loaded onto 12% polyacrylamide gel and assessed for the levels of the phosphorylated forms of ERK 1/2, MEK 1/2 and the src family proteins. The total amount of the same proteins was determined as a control. Fab D18 did not appear to induce any significant changes in the levels of phospho-ERK both in infected and uninfected GT1, whilst decreased levels of phospho-MEK were detected in GT1 cells upon D18 treatment (panel A). Regarding phospho-src proteins, increased levels were found in treated GT1 compared to untreated cells, both infected and uninfected (panel A). On the contrary, quinacrine treatment induces a significant hyper-stimulation of the ERK protein in GT1 cells and even increases the levels of the phospho-MEK in ScGT1 (panel B). Moreover, a strong decrease on phospho-src levels were found in infected GT1 upon drug treatment (panel B). Statistics were performed using Student's T-test on a set of three independent experiments; data were normalized on the total amount of proteins. * P < 0.05, ** P < 0.01 versus untreated controls, both for infected and uninfected cells.