Because we focused on plerixafor as the one CXCR4 inhibitor in clinical application in pediatric patients, we furthermore did not yet investigate whether compounds of distinct structure and purely antagonistic action at CXCR4 would elicit similar proliferative and migratory responses in CXCR4-high and -low Ewing sarcoma cell lines. Here, CXCR4 is linked to Ewing sarcoma.