CXCL13 and CXCL12 mRNA expression by NLCs. cDNA from purified NLCs from 10 patients with CLL (lanes 1-10) was examined for the expression of CXCL13 (top box) and CXCL12 (middle box) mRNA by RT-PCR. The specific PCR fragments (225 bp for CXCL13 and 233 bp for CXCL12) are visible in each of the 10 NLC samples. The bottom box displays PCR fragments of the expected size using GAPDH primers for the same NLC samples. On the left- and right-hand side of each of the boxes, the separation of the 100-bp marker DNA is displayed.