TABLE 1

Summary of biased agonism among several different μOR agonists with regard to different cellular responses

Relative efficacy ratios were extracted from quantitative studies in HEK-293 cells.

	DAMGO	Morphine	Methadone	Fentanyl	Etorphine	Herkinorin
[³⁵S]GTPγS binding	+++^{^a,^b}	+++^{^a,^c}	+++^{^a}	+++^{^a,^c}	+++^{^a,^c}	+++^{^b}
ERK1/2 phosphorylation	+++^{^d}	+++^{^d}	N.D.	N.D.	N.D.	+++^{^d}
μOR phosphorylation	+++^{^a,^d,^e}	+^{^a,^d,^e,^f}	+++^{^a}	+++^{^a}	+++^{^a,^f}	+^{^e}
β-Arrestin2 recruitment	+++^{^a}	+^{^a,^c}	+++^{^a}	++^{^a,^c}	+++^{^a,^c}	–^{^e}
μOR internalization	+++^{^a,^e}	+^{^a}	+++^{^a}	++^{^a}	+++^{^a}	–^{^e}