Table 2

Cross-resistance profile of the MCF-7 FLV1000 cell line

Drug	MCF-7 IC₅₀^a (μm)	MCF-7 FLV1000 IC₅₀^a (μm)	RR^b
Flavopiridol	0.18 ± 0.04	4.3 ± 2.4	24
Topotecan	0.03 ± 0.005	12.7 ± 3.8	423
Mitoxantrone	0.004 ± 0.002	2.7 ± 0.04	675
SN-38	0.002 ± 0.001	1.9 ± 0.3	950
Taxol	0.005 ± 0.0007	0.018 ± 0.009	4
5-FU	0.83 ± .021	8.3 ± 1.5	10

^a IC₅₀ values were determined by the sulforhodamine B assay.
^b Relative resistance values were determined by dividing the IC₅₀ for the resistant cell line by the IC₅₀ for the parental cell line. Experiments were performed at least three times.