These small-restricted areas around capillaries and pericytes topically overlap with hematopoietic progenitor cell niche [4] and are characterized by C-X-C motif chemokine 12 (CXCL12) expression [5], whose receptor CXCR4 is frequently overexpressed on primary tumor cells [6]. The gene discussed is CXCL12; the disease is neoplasm.