ACKR3 and neoplasm: Nevertheless, the connection between the CXCL12/CXCR4/CXCR7 axes and CSCs across different tumor entities is undeniable and backed by numerous studies showing that these axes regulate the maintenance of normal and tumoral stem cells in a direct way, and that these axes are involved in the activation and/or reinforcement of CSC features, including self-renewal, chemoresistance, metastasis, and the expansion of the CSC compartment as described above.