CHRNA4 and lung carcinoma: Different nAChR subunits appeared to influence the choice of pathway, in which subunit α3 was related to an activated PKC pathway in keratinocytes, subunit α5 was related to an activated JAK–STAT pathway in lung cancer, and subunit α7 was related to an activated PI3K‐Akt pathway in OSCC [5, 6, 40, 47, 56, 57].