Effects of 17-AAG and NVP-AUY922 on colony formation. Pancreatic cancer cell lines IMIM-PC-1, PANC-1, and CFPAC-1 (A) or colorectal carcinoma cell lines HT-29, SW620, LoVo, and Caco-2 (B) were seeded over agar plates in the presence of DMSO (control), 0.5 μM 17-AAG, or 0.1 μM NVP-AUY922. Colorectal cancer primary cultures HCUVA (C and D) were seeded over agar plates in the presence of DMSO (control), 0.5 μM 17-AAG, 2 μM 17-AAG, 0.1 μM NVP-AUY922, or 1 μM NVP-AUY922. Colonies were stained and counted after 14 days. Each treatment was performed in triplicate and error bars are the SEM. Difference between means was statistically significant (*P < .05, Mann-Whitney test).