Table 3.

Induced CYP activities.

	Induced CYP activities (20μM rifampicin) pmol/h/50,000 cells
	HepG2 cells	HepaRG cells	2D-cultured PHH	3D-cultured PHH
CYP1A2	nd	(0.51 ± 0.04)	(0.09 ± 0.01)	0.46 ± 0.02
				0.956
CYP2B6	nd	1.31 ± 0.04	1.7 ± 0.1	5.7 ± 0.1
		0.998	0.975	0.994
CYP2C9	nd	(0.12 ± 0.02)	(0.022 ± 0.002)	0.41 ± 0.01
				0.985
CYP2C19	0.21 ± 0.01	75.9 ± 1.8	1.96 ± 0.11	30.7 ± 1.7
	0.979	0.996	0.978	0.980
CYP2D6	nd	3.9 ± 0.2	0.35 ± 0.01	8.6 ± 0.4
		0.992	0.928	0.952
CYP3A4	1.1 ± 0.1	675 ± 20	129 ± 8	432 ± 17
	0.999	0.999	0.943	0.952

CYP activity in HepG2, HepaRG, 2D-, and 3D-cultured primary cryopreserved human hepatocytes (PHH) after treatment with 20 μM rifampicin for 72 h. Primary human hepatocytes used for 2D- and 3D-cultures were from the same batch of cryopreserved cells. Values presented are the metabolite formation rates and the regression coefficients (r²) of the metabolite-time curves after pre-treatment with rifampicin. Metabolite concentrations were determined by LC/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 (lacking basal activity).