Figure 4. Protected effects of NMN on 661W cells under oxidative stress are partially SIRT1 dependent. (A) NMN administration significantly increased 661W cell viability after ROS insult. ***p<0.001 to tBuOOH only group. N = 4 to 5 per group. (B) SRT2104, a SIRT1 direct activator, had a similar effect as NMN in protecting 661W cells from ROS insult. *p<0.05 to tBuOOH only group. N = 3 to 4 per group. (C) SIRT1 was knocked down by siRNAs. (D) Silencing SIRT1 by siRNAs attenuated the protective effect of NMN after ROS insult compared to the scrambled (SC) siRNAs control group. $p<0.001 to tBuOOH only group in SC siRNA condition. #p<0.001 to tBuOOH and NMN treated group in SC siRNA condition. N = 4 to 8 per group. Statistical significance was analyzed with one-way ANOVA followed by Tukey-Kramer adjustments. Data are mean ± SEM.