Fig. 7. Phosphorylation of ERK1/2 is required in EF-induced tumour cell migration. (A,B) An EF of 1.5 V/cm enhanced activation of ERK 1/2 in mammary breast cancer cells (MTLn3). The expression of active ERK1/2 increased within 15 minutes (m) of EF application, reached a maximum at 30 minutes that lasted for at least 1 hour, whereas the total level of ERK remained unchanged. Each membrane was a representative of two to three repeated experiments. (C) Inhibition of ERK partly inhibited EF-induced MTLn3 cell migration. Cells were pretreated with 50 µM U0126 (ERK-specific inhibitor) for 2 hours before application of 0.5 V/cm EF. *P<0.01 compared with EF alone; ^P<0.01 compared with no EF control.