Table 1.

Design of the in vitro experiment

Group no.a		Administrationb	Treatment days 1–3°		Treatment days 3–5c
			Drug	Concentrationd	Drug	Concentrationd
1	A	Sequential	MTA	0.04	GEM	0.04
	B					0.16
	C					0.64
	D					2.56
	E					10.24
2	A	Sequential	GEM	0.02	MTA	0.02
	B					0.08
	C					0.34
	D					1.36
	E					5.43
3	A	Simultaneous	–	–	MTA/GEM	0.02/0.04
	B					0.02/0.16
	C					0.02/0.64
	D					0.02/2.56
	E					0.02/10.24
4	A	Simultaneous	–	–	GEM/MTA	0.04/0.02
	B					0.04/0.08
	C					0.04/0.34
	D					0.04/1.36
	E					0.04/5.43

^a)Groups a–e were treated alike initially (days 1–3) and thereafter by different drug concentrations (days 3–5)

^b)3×10³ CC531 lacZ cells were grown for 24 h in 96-well plates and then exposed to treatment

^c)the first treatment period was terminated by changing the medium and adding fresh medium containing the second treatment

^d)µM