Western analysis was also utilized to assess whether overexpression of each individual repair gene resulted in altered endogenous expression of the other repair genes under both non-toxic and toxic conditions (24 hrs of 95% O 2 and 1000 Rad). Cells over-expressing the repair genes hOgg1, hMYH, hMTH, and hNTH did not lead to altered expression of the other endogenous repair genes under the above conditions when compared to each other or pSF91.1 vector control cells ( Figure 3A ,3B,3C and 3D). hOgg1's endogenous expression was below the level of detection. The pattern of endogenous expression of hNTH was consistent for each condition when comparing cells over-expressing hOgg1, hMYH, hMTH, and pSF91.1. Reduced expression of hNTH after exposure to 95% O 2 was noted.