CXCL12 and lung cancer: Although the exact CXCR4/CXCL12 signaling pathways implicated in lung cancer metastasis are almost unknown, CXCR4 regulates migration of lung cells through activation of Rac1 and matrix metalloproteinases (MMP-2 and MMP-14) [19], and through the combined action of ERK, IKK, NF-kappaB and integrins (ITGB1 and ITGB3) [22].