Double-positive cells are most sensitive to SIN-1–induced apoptosis.

Thymocyte CD4 and CD8 expression was analyzed on the viable cells (R2 gate). The distribution of the populations changed as early as 3 hours, with a fall in the percentage of double-positive cells (from 82% to 54% after 4 hours of treatment) and a corresponding increase in CD4⁺ and CD8⁺ cells. The data are representative of 3 individual experiments.