Figure 1.

E2A proteins are required for developmental arrest in the absence of TCR signaling. (A) Thymocytes from littermates that were heterozygous (+/−) or homozygous (−/−) for null mutations in the LAT and E47 genes were analyzed for surface expression of the CD4 and CD8 coreceptor molecules. Numbers above each plot indicate thymus cellularity. Results were representative of five separate experiments. (B) Thymocytes from mice that were wild type (+/+), heterozygous (+/−) or homozygous null (−/−) for the Fyn, Lck and E47 genes were analyzed for surface expression of the CD4 and CD8 coreceptor molecules. The E47+/+, Fyn−/−, Lck−/− mouse analyzed was from a separate litter from the other three mice. Numbers in each quadrant represent percentages of the total.