Table 4. Summary of secreted phosphoprotein 1 (SPP1) expression in the six species examined.

	Rat (mRNA)	Common marmoset (mRNA)	Squirrel monkey (mRNA)	Capuchin monkey (mRNA)	Rhesus macaque monkey (mRNA)	Rhesus macaque monkey (protein)	Human (protein)
Primary motor cortex (forelimb area: layer V)	−	−	+	++	+++	+++	+++
Brainstem (red nucleus)	+++	+++	+++	+++	+++	+++	+
Spinal cord (cervical cord)	++	++	++	++	++	++	++

Signal intensity was graded by visual evaluation as follows: +++, intense; ++, moderate; +, weak; −, not detectable. The SPP1 mRNA expression pattern data in the rat, marmoset, and rhesus macaque are from our previous report [11]