ACKR3 and cancer: Next, going out of the microarray data analysis, we shifted our attention to upstream regions of CXCR4 (chemokine (C-X-C motif) receptor 4 gene) and CXCR7 (chemokine (C-X-C motif) receptor 7 gene), as both are expressed in many types of cancer and have an important role in metastasis [27].