Table 1. ALDH⁺ and ALDH⁻ subpopulations of breast cancer cells were separated by flow cytometer and cultured in stem cell medium as described in Materials and Methods.

		SUM159	MDA-MB-231	SKBr3
250 cells/well	ALDH+	2.7±1.5*	15.7±1.5*	12.7±1.5*
	ALDH−	0	4.3±1.5	4.7±1.5
500 cells/well	ALDH+	20±4.9*	27.7±4.7*	14.7±1.2*
	ALDH−	3±2	6±6.1	7.3±1.5
1000 cells/well	ALDH+	27±2.6*	46±9.5*	23.3±4*
	ALDH−	7±2.6	27.7±3.1	9.3±2.1

The numbers of tumosphere generated per 250, 500 or 1000 cells were counted two weeks later. (*p<0.05 vs ALDH−).