The decreasing order of expression levels was as follows: CXCR4, CXCR7, CXCR2, CXCR6, CXCR5, CXCR3, and CXCR1. Although, CXCR2 expression is down-regulated in samples from most types of cancers compared to samples from normal subjects, it was found to be upregulated in AML (Figure 1B). Here, CXCR4 is linked to acute myeloid leukemia.