Defective positive and negative thymic selections in ΔSAM–SLP-76 knockin mice. (A) ΔSAM–SLP-76 knockin mice were crossed with HY-TCR transgenic mice. HY-TCR⁺ gated thymocytes from 4-week-old male (top) and female (bottom) HY-TCR⁺SLP-76^m/+ and HY-TCR⁺SLP-76^m/m littermates were analyzed for their surface expression of CD4 and CD8. The numbers represent the average percentages of the gated populations. (B) Surface expression of TCR-β, CD69, and CD5 on DP thymocytes from 4-week-old SLP-76^m/+ and SLP-76^m/m littermates.