Knockdown of PDK1 induced the downregulation of p‐eNOS Ser1177. HUVECs were transfected with siRNA targeting PDK1 or SIN1 and NC scrambled siRNA (100 nm) for 48 h, the transfection efficiency as well as the total and phosphorylated levels of Akt and eNOS were detected by western blot. (A) Western blot and quantitative analysis of the protein expressions of PDK1 and SIN1 in HUVECs transfected with different siRNA oligos. (B) Western blot and quantitative analysis of the protein expressions of p‐Akt Thr308, p‐Akt Ser473, and total‐Akt in HUVECs transfected with different siRNA oligos. (C) Western blot and quantitative analysis of the protein expressions of p‐eNOS Ser1177, p‐eNOS Thr495, and total‐eNOS in HUVECs transfected with different siRNA oligos. The relative levels of p‐Akt Thr308, p‐Akt Ser473, p‐eNOS Ser1177, and p‐eNOS Thr495 were quantified as the ratios of p‐Akt Thr308/Akt, p‐Akt Ser473/Akt, p‐eNOS Ser1177/eNOS, and p‐eNOS Thr495/eNOS, respectively. Data were expressed as mean ± SE, n = 4. Data were analyzed with one‐way ANOVA followed by Tukey's multiple comparisons test. *P < 0.05 vs. siRNA‐NC group; **P < 0.01 vs. siRNA‐NC group; ***P < 0.001 vs. siRNA‐NC group.