IVT products of Egr-1 or KSHV gL were evaluated by EMSA for DNA binding using several 25 bp digoxygenin (DIG)-labeled probes containing sequences from the ORF50P (Table 1) as per earlier studies [6] . For a supershift, the cellular lysate was incubated with rabbit monoclonal antibodies to Egr-1 or nonspecific IgG at 37uC for 30 min prior to the addition of the DIG-labeled probe. All samples were run on a 4% nondenaturing gel for approximately 1.5 h and transferred to a PVDF membrane. The protein:DNA interaction was detected using the CSPD detection system (Roche Applied Science).