CXCL12 and lung carcinoma: Preclinical and clinical studies support the viewpoint that chemokine CXCL12 (stromal cell-derived factor, SDF-1) and it’s receptor CXCR4 play a pivotal role in the progression and metastasis of lung cancers, particularly in non-small cell lung cancer (NSCLC) [23], [24], [25].