PCR analysis of plasmid existence in mouse spleen and the DLNs (popliteal and inguinal lymph nodes) 48 h after intramuscular delivery of plasmids. Lane 1, DNA marker DL2000; Lane 2, the spleen DNA samples from pCCL19/GFP-immunized mice; Lane 3, the spleen DNA samples from normal mice spiked with pCCL19/GFP; Lane 4, the spleen DNA samples from PBS-immunized mice; Lane 5, the DLNs DNA samples from normal mice spiked with pCCL19/GFP; Lane 6, the DLNs DNA samples from pCCL19/GFP-immunized mice; and Lane 7, the DLNs DNA samples from PBS-immunized mice.