Table 1.

Limiting number of each lineage readout from proT cells in stromal cell culture

Population	Mouse	Readout lineage, 1 in
		G/M cells	NK cells	B cells
ProT1	WT	500	22	150
	IL-2Rβ transgenic	10	60	>1,000*
ProT2	WT	∞†	31	∞†
	IL-2Rβ transgenic	8	54	∞†

One to 40 cells were clone-sorted into each well of 96-well plates layered with OP9 stromal cells and cultured for 7–10 days in the presence of SIF, FL, IL-7, and human IL-2. Positive readout was determined by microscopic observation. Outcome lineage was confirmed by flow cytometric analysis. The limiting number was obtained as described (14). 

^*Too few positive events to determine the limiting number. 

^† No positive readout was observed.