Table 1. Drug-tolerant Du145 cells possess much reduced tumorigenic potential.

Cell typea	Cell#	Incidence (%)b	TIFc	Latency(d)d	Termination(d)d	Weight (g)e
Du145	100	7/7 (100)	1/175 (1/66–1/467)	63	90	0.07±0.03 (0.03–0.12)
	1000	7/8 (87.5)		36	60	0.42±0.33 (0.10–0.95)
	10000	8/8 (100)		27	59	0.50±0.35 (0.12–0.97)
	100000	7/8 (87.5)		21	52	0.39±0.17 (0.18–0.65)
Du145-VP16	100	1/8 (12.5)	1/62,453 (1/26,455–1/147,436)	92	117	1.45
	1000	0/8**			60
	10000	0/8**			59
	100000	5/6 (83.3)		51**	52	0.06±0.05 (0.02–0.14)**
Du145-VP16 (2 mo.)#	1000	1/6 (16.7)*	1/30,110 (1/7,199–1/125,948)	83	127	0.01
	10000	1/6 (16.7)*		45	127	0.2
Du145-STS	100	1/8 (12.5)	1/971 (1/421–1/2,241)	52*	90	0.16
	1000	5/8 (62.5)		58*	66	0.07±0.02 (0.04–0.09)*
	10000	3/8 (37.5)*		48*	66	0.13±0.14 (0.05–0.29)*
Du145-Paclitaxel	100	0/8**			105
	1000	0/8**			60
	10000	0/8**			60
	100000	0/6**			52
Du145-WP1102	100	2/4 (50)	1/45,787 (1/15,313–1/136,901)	58	90	0.03±0.01 (0.02–0.04)*
	1000	2/4 (50)		58**	66	0.37±0.13 (0.27–0.46)
	10000	2/4 (50)		58**	66	0.11±0.12 (0.02–0.19)*
	100000	3/4 (75)		31*	52	0.19±0.24 (0.01–0.46)
Du145-WP1103	100	0/8**			99
	1000	0/8**			60
	10000	0/8**			60
Du145-WP1103 (2 mo.)#	1000	0/6**			108
	10000	0/6**			108

^aParental Du145 or drug-tolerant Du145 cells were s.c implanted in 50% Matrigel, at the numbers indicated, in NOD/SCID mice. In the two experiments marked by #, cells were first cultured in drug-free medium for 2 months prior to injections.

^bTumor incidence (% of tumor development/injections).

^cTumor-initiating frequency, as determined using the L-Calc™ software (Stemcell Technologies). The ranges were indicated in the parentheses.

^dTumor latency (mean time in days from injection to when tumors were first palpated) and termination time (days from injection to when animals were sacrificed).

^eMean ± S.D (ranges in parentheses). Note that tumor weights sometimes varied greatly among different cell number groups. For statistical analyses, Fisher's Exact Test was used to compare tumor incidence and Student t-test was used to compare tumor weights and latencies.

*P<0.05;

**P<0.01, when compared with the parental Du145 cells of the same number.