Table 4.

Summary of in vitro studies assessing functional differences among DRD4 VNTRs 48 bp.

Authors	References	Years	Technique	Functional response	Cells	Agonist
Asghari V et al.	[1]	1994	[3H]spiperone binding RIA	Non-specific	COS-7	Dopamine
Asghari V et al.	[2]	1995	[3H]spiperone binding RIA	cAMP inhibition	CHO-K1	Dopamine
Sanyal S & Van Tol HH	[3]	1997	[3H]spiperone binding RIA	cAMP inhibition	GH4C1	Dopamine
Oldenhof J et al.	[4]	1998	[3H]spiperone binding RIA	cAMP inhibition	CHO-K1	Dopamine
Jovanovic V et al.	[5]	1999	[3H]spiperone binding RIA	cAMP inhibition	CHO-K1	Dopamine
Watts VJ et al.	[6]	1999	[3H]spiperone binding RIA	cAMP inhibition	HEK 293	Dopamine
Kazmi MA et al.	[7]	2000	[3H]spiperone Ca2+ channel flux assay	Ca2+ channel current inhibition	HEK 293T	Quinpirole
Gilliland SL et al.	[8]	2000	[35S]GTPγS agonist stimulated binding assay	Gi protein	CHO-K1	Quinpirole
Czermak C et al.	[9]	2006	[35S]GTPγS agonist stimulated binding assay	Gi protein	CHO-K1	Dopamine
Van Craenenbroeck K et al.	[10]	2011	[35S]GTPγS agonist stimulated binding assay	Non-specific	HEK 293T	Quinpirole
Borroto-Escuela DO et al.	[11]	2011	BRET50 assay	Receptors ratio	HEK 293T	nr
Van Craenenbroeck K et al.	[10]	2011	BRET50 assay	Non-specific	HEK 293T	Quinpirole
Sanchez-Soto M et al.	[12]	2016	BRET50 assay	cAMP inhibition	HEK 293T	Dopamine
Sanchez-Soto M et al.	[13]	2018	BRET50 assay	Gi protein	HEK 293T	Dopamine
Sanyal S & Van Tol HH	[3]	1997	Luciferase reporter assay	cAMP inhibition	GH4C1	Quinpirole
Schoots O & Van Tol HH	[14]	2003	Luciferase reporter assay	Expression	GH4C1	nr
Van Craenenbroeck K et al.	[15]	2005	Western analysis	Expression	CHO-K1	Quinpirole
Gonzalez S et al.	[16]	2012	Transient transfection	MAPK activation (ERK 1/2 phosphorylation)	HEK 293T	RO-10-5824

RIA radioimmunoassay, BRET bioluminescence resonance energy transfer; nr non-reported.