CXCR4 and acute myeloid leukemia: OCI-AML-3 and MONO-MAC-6 cell lines showed elevated levels of CXCR4 expression, while the HEL cell line had negligible levels of CXCR4 expression (OCI-AML-3: 6.2 ± 1.3 of RFI; MONO-MAC-6: 4.0 ± 0.9 of RFI; HEL: 1.5 ± 0.0 of RFI).