Table 4. Microarray gene expression profilings tageting HSC based on relative comparison.

Year	Group	Platform	HSC	Compared to	# of probes	# of genes	Ref
2002	Hood	House made	Rhlow KLS	Rhhigh KLS		5000	[21]
2002	Lemischka	Affymetrix MU-U74-2 A∼C	Rhlow KLS	Variou type of cells	36000	6000+18000 EST	[22]
2003	Akashi	Affymetrix MU-U74-2 A∼C	Thy1.1low Rhlow KLS	MPP, CMP, CLP	36000	6000+18000 EST	[23]
2003	Weissman	Clontech Atlas Mouse cDNA array	Thy1.1low KLS	CMP, CLP, GMP, MEP, ProT, ProB		1200	[24]
2005	Weissman	Stanford Microarray Facility 42 kmouse cDNA array	Thy1.1low Flk2− KLS	Thy1.1low Flk2+ KLS, Thy1.1−Flk2+ KLS	42000		[25]
2005	Weissman	Affymetrix Mouse 430 2.0	CD34− Flk2− KLS (young)	CD34− Flk2− KLS (old)	45000	34000	[26]
2006	Goodell	Affymetrix Mouse U74A	SP Sca1+ Gr1−	CD8+ T cell	45000	34000	[27]
2007	Goodell	Affymetrix Mouse 430 2.0	SP KLS	Erythrocyte, Granulocyte,Native T cell, Activated T cell,Activated B cell, Monocyte,NK cell	45000	34000	[28]

KLS: c-Kit+ Lin− Sca-1+; MPP: multipotent progenitor; CMP: common myeloid progenitor; CLP: common lymphoid progenitor; GMP: granulocyte/macrophage progenitor; MEP: megakaryocyte/erythrocyte progenitor; Pro T: progenitor T cell, Pro B: progenitor B cell.