As shown by the Annexin-V/PI apoptosis assay, while ABT263 (2 μm) or AXIT (1 μm) alone could lead to enhanced apoptosis in both HCT116 and HCT15, in the ABT263 + AXIT combination, much higher fractions of the cells underwent apoptosis compared with single drug treatment, suggesting that the combination enhances apoptosis of KRAS-mutant colon cancer cells (Figure 2A,B). Here, KRAS is linked to malignant colon neoplasm.