Figure 5: Protandim treatment following Nrf2 silencing protected HCAEC against an oxidative challenge; however, protection following Nrf2 silencing was significantly diminished compared to controls. (a) Silencing of Nrf2 resulted in a significant increase in the number of cells undergoing apoptosis in response to an oxidative challenge regardless of Protandim. (b) In no RNA, control RNA, and Nrf2 RNA conditions, significantly fewer cells underwent apoptosis when treated with Protandim prior to an oxidative stress. The no RNA condition and control RNA were not significantly different from each other with or without Protandim. In Nrf2 siRNA conditions, % TUNEL-positive (+) nuclei were significantly higher than no RNA and control RNA conditions with and without Protandim- ( = 15–19 fields) (c) The percent protection by Protandim was not significantly different between no RNA and control RNA conditions. The protection afforded by Protandim in the Nrf2 siRNA condition was significantly less compared to both no RNA and control RNA conditions. Data are presented as means + SE. * between indicated groups, ** between indicated groups. # compared to within RNA condition control (no Protandim), ## compared to within RNA condition control (no Protandim). Ptd: Protandim, Ctr: No Protandim.