Expression of EP4 expression was involved in the PGE2‐induced oncogenic gene, such as phosphoinositide‐dependent kinase‐1 (PDK1) and α7 nicotinic acetylcholine receptor (nAChR), expression through inhibition of c‐Jun in bronchial epithelial and lung cancer cells 33, 34, 55. This evidence concerns the gene PTGER4 and lung carcinoma.