MAPK3 and neoplasm: Typically, activated EGFR signal pathway plays the important roles in cell proliferation, differentiation and others.20 Merlin, a tumour suppressor, also regulates proliferation in many cell types.21 Next, we detected the phosphorylation levels of EGFR, ERK1/2 (p44/p42) and Merlin in normal‐ and high‐density cells.