Baf57 mutations impaired CD8 expression, which was preventable by tamoxifen (TAM). Thymocytes were stained with T-cell receptor (TCR) CD4, CD8, CD25 and CD44 antibodies. The early thymocyte population, which are large cells (defined by high forward scatter or FShi) that lack TCR, CD25 or CD44, were resolved into GFP- and GFP+ subsets (column 1) before analysis of CD4/CD8 expression (columns 2 to 3). The genotype symbols are as described in Figure 4A. Of note, a CD4- CD8+ population, which made up 12% of the early thymocytes in WT mice (blue circle in row A, column 2), was absent in Baf57F/F; CD4-Cre mice, and partially depleted by Baf57ΔR, with unknown mechanisms. At least three mice of each genotype were analyzed. Shown is a representative experiment.