Thymocyte development in ΔSAM–SLP-76 knockin mice. (A) Total numbers of different thymocyte populations from 4-week-old SLP-76^m/+ and SLP-76^m/m littermates. Five mice for each genotype were analyzed. Statistical analysis was performed using 2-tailed Student t test. *P < .05; **P < .01. (B-D) Thymocytes from 4-week-old SLP-76^m/+ and SLP-76^m/m littermates (5 mice for each genotype) were analyzed by flow cytometry. FACS plots shown are from 1 representative of each genotype. (B) Surface expression of CD4 versus CD8 on total thymocytes. (C) Expression of CD25 versus CD44 on CD4⁻CD8⁻ DN thymocytes. (D) Expression of TCR-β versus HSA on CD4⁻CD8⁺ thymocytes. The numbers in each panel represent the average percentages of the gated populations.