While truncation of RANTES by DPPIV increases its chemotactic activity via the C-C chemokine receptor 5 (CCR5) and thereby prevents HIV infection[14,15], cleavage of SDF-1α by DPPIV leads to reduced chemotactic activity and consequently promotes HIV infection via the C-X-C chemokine receptor 4 (CXCR4) [16]. The gene discussed is CXCL12; the disease is HIV infectious disease.