ROS modifiers inhibited estrogen-induced colony formation.

<p>For investigating inhibition of 4-OH-E2-induced cell transformation by ROS modifiers, MCF-10A cells were transfected with 100 MOI adenovirus expressing catalase or MnSOD or treated with an antioxidant Ebselen (40 uM). Cells overexpressing catalase or MnSOD or treated with Ebselen were exposed to a carcinogenic regimen of estrogen as described in the legend of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0054206#pone-0054206-g002" target="_blank">figure 2</a>. Anchorage independent growth was assessed in soft agar after 21 days. Images were acquired by using an Olympus C-5060 digital camera attached to the Nikon TE2000U inverted microscope with a 4x objective (bottom panel shows representative pictures of colonies in soft agar in both 2A and 2B). Colony efficiency was determined by a count of the number of colonies >63 um in diameter and data expressed as mean of five wells +/− S.D. *P<0.05, significantly different from 4-OH-E2 treatment. **P<0.05 indicates significantly different from control.