Activation of EGFR signaling pathways upon EGF stimulation in RBE and MMNK-1 cells. (A) Expression of pY1068, total EGFR, phospho-p44/42 MAPK (p-p44/42 MAPK), and total p44/42 MAPK before and after 0.5, 1 and 2 hr of EGF stimulation in RBE cells (closed circles) and MMNK-1 cells (open circles) as detected by Western blotting. (B) Left: quantification of pY1068 expression normalized to total EGFR. All values are presented as the relative value to the value of pY1068/total EGFR in RBE cells without EGF stimulation. Right: quantification of p-p44/42 MAPK expression normalized to total p44/42 MAPK. All values are presented as the relative value to the value of p-p44/42 MAPK/total p44/42 MAPK in RBE cells without EGF stimulation. *p < 0.05. All results shown are representative of three independent experiments.