CXCR4 and AIDS: Interestingly, in the HSPC model employed here, the dominant expression of the CXCR4 coreceptor over the CCR5 coreceptor suggests that hematopoietic progenitors may be preferentially infected by CXCR4-tropic HIV, which is linked to disease progression and immune failure in HIV/AIDS (Delobel et al., 2006).