CXCR4 and cancer: The CXC chemokine receptor subtype 4 (CXCR4) and subtype 7 (CXCR7; also known as Atypical Chemokine Receptor 3, ACKR3) constitute an interesting pair as they both recognize a common natural chemokine agonist, referred to as CXCL12, also known as the stromal cell-derived factor 1 (SDF1)12 (Fig. 1a) These two receptors are involved in various aspects of cancer onset and progression, cardiac disorders and autoimmune diseases13.