CYCS and colorectal cancer: This hypothesis is supported by the finding that BORIS silencing increased the inhibition of colorectal cancer cell growth by 5-FU (Fig. 6a), which inhibits DNA synthesis and increases the production of ROS32, and that overexpression of BORIS but not BORIS-ZFdel attenuated the suppressive effect of 5-FU on colorectal cancer cell growth and cytochrome c release (Figs 6 and 7).