Vitamin C selectively kills KRAS mutant colon cancer cells A. Apoptosis-induced by vitamin C in normal human immortalized Colonocytes (HCEC), SW480 and DLD1 cancer cell lines were annalyzed by Annexin-PI assay. Each cell line (2,5 105 cells) was incubated with vitamin C (10 mM) and PBS for controls for 24 h. Apoptosis in each cell line was measured by staining with FITC-conjugated Annexin-V and Propidium Iodide (PI) using a Sigma-Aldrich Apoptosis kit. The populations of cells (annexin-V positive/PI negative) and late apoptotic cells (annexin-V positive/PI positive) as a percent of total cells were evaluated. Vitamin C displayed a selective killing effect on SW480 and DLD1. One-way ANOVA followed by Dunnett's post-test for multiple comparisons. *p< 0.05, **p < 0.001, n = 3. B.images show apoptotic activity in KRAS mutant SW480 and DLD1 cell lines after vitamin C treatment (10 mM) for 24 h. C. vitamin C treatment at different concentrations were carried out with HCEC and DLD1 and SW480 cancer lines. All cell lines were exposed to ascorbate at 1, 3 and 5mM, for 24 h. Then, cells were tripsinized and fixed with trypan blue solution (Sigma-Aldrich). Cell counting was carried out using a neubauer chamber (SigmaAldrich) One-way ANOVA followed by Dunnett's posttest for multiple comparisons < 0.05, **p < 0.001, n = 3. D. HCEC, SW480 and DLD1 cells were treated with 5Mm and 6Mm vitamin C respectively for 4,6, 12 and 24 h. Then, cells were tripsinized and fixed with trypan blue solution (SigmaAldrich). Cell counting was carried out using a neubauer chamber (SigmaAldrich) One-way ANOVA followed by Dunnett's posttest for multiple comparisons. *p < 0.05, **p < 0.001, n = 3.