CXCR4 overexpression can only be observed when the tumor relapses, indicating that E2A-PBX1 works together with other synergistic factors to regulate the expression of CXCR4 and enhance the drug resistance of tumor cells (Eldfors et al., 2017; Szekely et al., 2018; Nengroo et al., 2021). Here, CXCR4 is linked to neoplasm.