Plasmacytoma biopsy samples before and after injection of AdCAIL-2 were PCR-amplified using primers specific for AdCAIL-2 (A), Ad5 E1 (B), or B-actin (C). PCR products were detected using internal radiolabeled probes. Lane 1, tumor biopsy sample preinjection; lane 2, tumor biopsy sample 7 days postinjection; lane 3, tumor at autopsy; lane 4, negative control—mock DNA extraction from autopsy tumor; lanes 5 and 6, positive controls. No E1 sequences from wild-type adenovirus were detected in the tumor. In contrast, AdCAIL-2 was readily detected in the postinjection biopsy samples.