Table 2.

Basal CYP activities.

	Basal CYP activities pmol/h/50,000 cells
	HepG2 cells	HepaRG cells	2D-cultured PHH	3D-cultured PHH
CYP1A2	nd	(0.46 ± 0.02)	(0.09 ± 0.01)	0.22 ± 0.02
				0.932
CYP2B6	nd	0.33 ± 0.02	0.54 ± 0.04	2.11 ± 0.07
		0.999	0.905	0.985
CYP2C9	nd	(0.11 ± 0.01)	(0.016 ± 0.002)	0.16 ± 0.01
				0.854
CYP2C19	0.16 ± 0.01	18.5 ± 1.0	0.47 ± 0.04	3.7 ± 0.1
	0.976	0.939	0.815	0.978
CYP2D6	nd	0.69 ± 0.06	0.25 ± 0.01	6.2 ± 0.3
		0.823	0.950	0.935
CYP3A4	0.64 ± 0.04	85.6 ± 4.5	27.4 ± 1.5	60.4 ± 1.5
	0.645	0.991	0.903	0.993

Basal CYP activity in HepG2, HepaRG, 2D-, and 3D-cultured primary cryopreserved human hepatocytes (PHH). Primary human hepatocytes used for 2D- and 3D-cultures were from the same batch of cryopreserved cells. Values presented are the metabolite formation rates (see Figure 2) and the corresponding regression coefficients (r²) of the metabolite-time curves. Metabolite concentrations were determined by LC-MS/MS. Data are presented as mean ± SEM of at least three independent experiments. Values in brackets are based on measurements of the last experimental time-point only, concentrations of all earlier time-points were below LLOQ. nd = not determinable (i.e., lacking basal activity).