Figure 5.

Effect of ubiquitin-specific protease 8 inhibitor on proopiomelanocortin expression and adrenocorticotropic hormone secretion. AtT20 cells were incubated for 4 and 24 h with 1–20 μmol/L ubiquitin-specific protease 8 inhibitor; proopiomelanocortin mRNA expression was assessed by quantitative reverse transcription polymerase chain reaction (a and b). Adrenocorticotropic hormone levels were measured in conditioned medium by enzyme-linked immunosorbent assay in six independent experiments in three replicates (c and d). * P<0.05, **P <0.01, *** P<0.001.