Figure 1.

The Egr-1 gene is rapidly induced after TCR-mediated activation of the DPK double positive cell line. (A) Total RNA isolated from DPK cells cultured with immobilized anti-CD3ε mAb for the indicated times (shown in hours), was subjected to RT-PCR analysis using Egr-1 or CD4 primers. (B) Electrophoretic mobility shift assay using nuclear lysates prepared from DPK cells 8 h after activation by immobilized antiCD3ε mAb. Probes contained a single Egr-1 binding site (left) or overlapping Egr-1 and Sp1 sites (right). (C) DPK cells were cultured with DCEK-ICAM fibroblast antigen presenting cells and 1 μm pigeon cytochrome c peptide for the indicated times. Total RNA was isolated and subjected to a competitive RT-PCR assay (see Materials and Methods). Note the different scales for Egr-1 and CD4 mRNA expression.