Table 1. Average IC₅₀ values of STX140, STX243, STX66, paclitaxel, ENMD1198, vinorelbine and colchicine in (a) MCF-7 and (b) MDA-MB-231 cells.

MCF-7 cells Avg IC50 values (μM)	Mock	pALTER-TUBB3	siRNA-tubb3
(a)
STX140	0.98	1.06	0.92
STX243	0.69	0.81	0.73
2-MeOE2	0.99	0.97	0.98
Paclitaxel	7.2 × 10−6	1 × 10−4**	4.8 × 10−6*
Vinorelbine	0.06	1**	0.01*
ENMD1198	0.57	0.61	0.45
Colchicine	0.024	0.029	0.029
MDA-MB-231 cells Avg IC50 values (μM)	Mock	pALTER-TUBB3	siRNA-tubb3
(b)
STX140	0.05	0.08	0.07
STX243	0.08	0.10	0.09
2-MeOE2	0.99	0.98	0.99
Paclitaxel	2 × 10−6	4 × 10−6***	<1 × 10−7**
Vinorelbine	0.12	0.25**	0.12
ENMD1198	0.08	0.09	0.09
Colchicine	0.037	0.042	0.029

Cells were transfected with pALTER-TUBB3 or siRNA-tubb3. They were then exposed to STX140, STX243, paclitaxel, STX66, ENMD1198, vinorelbine or colchicine for 4 days and the IC₅₀ values were obtained from a graph of percent proliferation vs inhibitor concentration and calculated using Prism (Graphpad Software). ^***P<0.001, ^**P<0.01 and ^*P<0.05.