Upregulation of CXCR4 expression has been observed in different human cancers [104], and the CXCL12/CXCR4 axis is often considered a hallmark of cancer aggressiveness and correlates with tumor size, grade and recurrence [105,106,107,108], poor prognosis [106] and low survival [109]. The gene discussed is CXCR4; the disease is cancer.