Thymocyte differentiation arrest induced by p16inka in TAL1xLMO1 mice depends on p16INK4A expression level. Example of flow-cytometry analysis of cell-surface markers on TAL1xLMO1xp16inka thymocytes stained with (A) anti-CD4 and anti-CD8 antibodies or (B) anti-CD25 and anti-CD44 gated on CD3−, CD4−, and CD8− cells. Percentages are indicated in the quadrants.