Table 2. Modulation of phase I metabolism enzymes in HepG2 and A549 cells following exposure to 0.2 µM B[a]P.

	HepG2			A549
Exposure time (h)	CYP1A2	CYP3A4	EPH	CYP1A2	CYP3A4	EPH
0.5	0.66±0.28	1.94±0.12 *	0.82±0.23	2.41±1.34	2.10±0.86	0.67±0.28
1	1.52±0.93	0.96±0.55	0.60±0.41	1.16±0.58	1.18±0.39	0.35±0.12
2	1.70±0.30 *	1.56±0.28	0.80±0.21	1.68±0.85	1.01±0.32	0.75±0.19
4	4.47±0.31 *	1.59±0.17	0.80±0.11	1.40±0.67	1.06±0.37	0.71±0.21
6	7.39±0.73 *	1.43±0.21	0.93±0.14	1.34±0.78	1.37±0.41	0.90±0.13
14	4.76±0.94 *	1.42±0.22	0.91±0.09	0.67±0.46	1.38±0.51	0.72±0.22
24	4.88±0.49 *	2.12±0.07 *	0.80±0.14	1.61±0.85	1.98±0.89	0.75±0.31

^*: significantly different from DMSO control of concerned cell line (p<0.05).