CXCR4 and squamous cell carcinoma: A functional in vitro study using a human squamous carcinoma cell line corroborated with human pathological findings and revealed that snail increases the CXCR4 expression on tumor cells in the presence of TGF-β1 and the EMT process augments tumor cell migration through the CXCR4–SDF-1 axis (Figure 1B) (18).