CXCL12 and gastric cancer: The involvement of CXCL12/CXCR4 signaling in tumor invasion and metastasis was also confirmed in other several cancer types, including non-small cell lung cancer (NSCLC), gastric cancer (GC) [24,25], and prostatic carcinoma (PCa) [26], and also linked to the promotion of cancer stem cell proliferation [27,28].