FIG. 1.

Enhanced apoptosis of DP thymocytes in Id1 transgenic mice. (A) EMSA with nuclear extracts prepared with total thymocytes from wild-type and heterozygous Id1 transgenic mice. The E-box and Oct-1 probes were as described previously (24). As a control, EMSA with a nuclear extract from the WEHI231 B-cell line was performed with or without anti-E47 antibodies to supershift the E47 containing complexes as marked with arrows. The amount of Oct-1 binding complex serves as a control for the amount of nuclear extract in each sample. (B). Thymocytes from wild-type and Id1 transgenic mice on the FVB/N background were stained with the indicated antibodies. The number in each quadrant is the percentage of the subset of thymocytes. (C). Sorted viable DP thymocytes were stained with Annexin V-FITC with or without 8 h of culture at 37°C. The percentage of Annexin-positive cells is shown on top of the gate.