Previous study reported that the cell surface CXCR5 could be induced to upregulate on cancer cells after the in vivo engraftment, and quickly dropped after ex vivo culture.25 Based on this consideration, tumor tissues were obtained at 1 week after s.c. inoculation in BALB/c mice, and tumor cells were isolated by collagenase digestion for CXCR5 surface staining. Here, CXCR5 is linked to cancer.