Figure 8

Signalling pathways involved in neurotensin-stimulated DNA synthesis in HCT116 cells. A, Effect of MEK inhibition on basal and neurotensin (NT)-induced DNA synthesis. Quiescent cells were pretreated with vehicle (0.5% DMSO) or 50 μM PD98059 (PD) for 30 min before stimulation with the vehicle (0.9% NaCl) or 1 μM NT. Data are presented as per cent of control values of six independent experiments. Error bars indicate S.E.M. * Significantly different from vehicle-treated control (p < 0.05), #significantly different from control cells pretreated with PD98059 (p < 0.05). B, Effect of EGFR kinase inhibitors on DNA synthesis induced by neurotensin. Quiescent cells were pretreated for 30 min with vehicle (0.5% DMSO), 10 μM gefitinib (Gef), or 10 μM AG1478 prior to stimulation with 1 μM NT. Data are presented as per cent of control values of four (AG1478) or seven (gefitinib) independent experiments. Error bars indicate S.E.M. * Significantly different from vehicle-treated control (p < 0.05), #significantly different from control cells pretreated with gefitinib or AG1478 (p < 0.05). C, Effect of phosphoinositide 3-kinase inhibition on DNA synthesis induced by neurotensin. Quiescent cells were pretreated for 30 min with vehicle (0.5% DMSO) or 1 μM wortmannin (WM) prior to stimulation with 1 μM NT. DNA synthesis was determined by [3 H]thymidine incorporation as described in the legend of figure 1. Data are presented as per cent of control values of six independent experiments. Error bars indicate S.E.M. * Significantly different from vehicle-treated control (p < 0.05), #significantly different from control cells pretreated with wortmannin (p < 0.05).