Pre-treatment of doxycycline. 2 × 104 HT 29 cells/ml were treated with 10 μg/ml of doxycycline for 3 days in the wells of 6 well plates followed by treatment with different concentrations of cisplatin and oxaliplatin for 24 hours. In similar settings, another set of experiments was established without pre-treatment of doxycycline for 3 days. The cytotoxicity was assessed with Alamar blue assay according to the manufacturer's instructions. Data are depicted as means of six experiments ± standard deviation. (p = 0.003 for cisplatin and p = 0.003 for oxaliplatin experiments). (* - Denotes statistically significant difference in the activity).