Figure 6. Suppression of senescence-associated SIRT4 upregulation in γ-irradiated primary human dermal fibroblasts by oligonucleotides mimicking the function of endogenous miR-15b. Concomitant upregulation of SIRT4 expression (A) and downregulation of miR-15b levels (B) in human dermal fibroblasts two, four, and six days upon γ-irradiation (single dose of 20 Gy; n=6, mean ± s.d.). To evaluate statistical significance, ANOVA on ranks were performed (*p<0.05). (C) Extrinsically applied miR-15b mimics inhibit the senescence-associated upregulation of SIRT4 mRNA levels in human dermal fibroblasts upon γ-irradiation (single dose of 20 Gy) as compared to irradiated cells transfected with control mimics (n=5 independent experiments, mean ± s.d.). To evaluate statistical significance, ANOVA SNK were performed (**p<0.01).