The cytoplasmic domain is coupled to the cytoskeleton and some downstream signalling molecules, such as tyrosine kinase and serine‐threonine kinase, which can promote tumour attachment, proliferation, invasion and migration.22, 23 B. Tian and T. Shibue reported that β1 integrin activates FAK and PI3K/AKT and promotes cell survival.15, 24 In our erlotinib‐resistant cell lines, AKT phosphorylation was also observed with continuous erlotinib treatment. This evidence concerns the gene PTK2 and neoplasm.