Fig 4. Oxidative stress and endoplasmic reticulum (ER) stress did not induce DNA methylation of Ins1 promoter.

INS-1 cells were cultured for 14 days under the following conditions: (A and B) with H₂O₂ in 11.2 mmol/l glucose; (C and D) with N-acetyl-cysteine (NAC) in 22.4 mmol/l glucose; (E and F) with thapsigargin in 11.2 mmol/l glucose; and (G and H) with tauroursodeoxycholic acid (TUDCA) in 22.4 mmol/l glucose. Insulin mRNA levels (A, C, E, and G) were examined by real-time PCR. DNA methylation of the Ins1 promoter (B, D, F, and H) was examined by pyrosequencing analysis. All results are means ± SEM (n ≥ 4). Asterisks indicate statistically significant differences (*p < 0.05, **p < 0.01).