AXL and lung cancer: Of them, focal adhesion kinase (FAK) is a non-receptor tyrosine kinase, upregulated in NSCLCs, and involved in neoplastic transformation, invasion, and metastases, such as cell adhesion, migration and apoptosis [20]; PXN is known to be associated with lung adenocarcinoma progression [21]; MET is important in promoting tumor growth, progression and invasion in lung cancers [22]; RON (MST1R) is involved in tumor growth and metastasis [23, 24]; EPHA2 is overexpressed in 70% of NSCLC and strongly associated with patient's survival [25]; AXL is an emerging drug target in NSCLC and SCLC [26, 27].