Effect of GLI antagonists JK184, HPI-1, HPI-4 and GANT61 on SUM149, MDA-MB-231 and SUM159 colony formation. For colony formation, cells were seeded in 6-well plates, treated with the indicated compounds for 5–14 days, fixed, colonies stained and counted. (A) Representative images for SUM149 and MDA-MB-231 colonies stained with crystal violet. A minimum of two independent experiments were carried out. (B) SUM149 and MDA-MB-231 percent colony formation relative to vehicle. (C) Representative images for SUM159 colonies and percent colony formation relative to vehicle. Data represents mean ± SD percentage of colonies relative to vehicle/untreated for a minimum of three wells. One-way ANOVA with Tukey’s post-test (*p<0.05, **p<0.005, ***p<0.0005 and ****p<0.0001; significantly different from respective controls).