FIGURE 5.

CXCR7 expression in head and neck cancer cells. A, human head and neck cancer cell lines and primary keratinocytes were tested for CXCR7 and CXCR4 mRNA expression by quantitative RT-PCR. Expression was related to the β-actin content. A.U., arbitrary units; OE, VU-SCC-OE. B, ¹²⁵I-CXCL12 radioligand binding with head and neck cancer cells. Specific CXCR7 expression was confirmed using the cold chemokines CXCL12 and CXCL11 and CXCR7-specific NB3. TB, total binding. C, growth rate of 22A cells injected subcutaneously in the flank of nude mice. D and E, immunofluorescence staining of CXCR7 protein with C1C2 polyclonal antibody on Fadu-derived (D) and 22A-derived (E) xenograft tumors developed in nude mice.