Table 1.

List of tissues in which the SP has been identified.

Source	Species	References
Hematopoietic stem/stromal cells
Bone marrow	Human Murine Rhesus monkey	([12]; [32]; [33]; [21]; [24]; [13])
Peripheral blood	Human	[34]
Umbilical cord blood	Human	[35]
Embryonic stem cells
Immortalized cell lines	Mouse Human	([20]; [31])
Multipotent stromal/stem cells
Cells derived from ESC lines	Murine	([20]; [31])
Bone marrow	Canine	[36]
Neural tissue (neural stem cells)	Human Murine	([37]; [7]; [38])
Dental pulp	Human Canine Porcine	([9]; [36]; [39]; [40]; [41]; [42])
Cardiac tissue	Human Murine	([20]; [43]; [44]; [45]; [38])
Lung tissue	Human Murine	([46]; [47]; [38])
Muscle tissue	Murine	([48]; [24]; [49]; [50]; [51]; [38])
Adipose tissue	Human Murine Rat Canine	([36]; [52]; [29]; [53]; [54])
Epidermis (keratinocytes)	Human	[55]
Endometrium	Human Murine	([30]; [56])