Posttranscriptional expression of GK gene is compromised in GKRP-mutant mouse liver. (A) GK expression in wild-type liver; GK mRNA (empty bars) and protein (filled bars) levels are enhanced by insulin. (B) GK expression in mutant mouse liver; GK mRNA (empty bars) is increased by insulin, whereas GK protein (filled bars) is not. Data are presented as -fold over time-0 wild-type mouse liver, with wild-type value taken as 1.0. Mean ± SEM, n = 3 for wild type and n = 3 for mutant per each time point. (C) Densitometric quantitation of the Western blot of extracts prepared from primary hepatocytes cultured in media containing 5.5 mM glucose, showing decreased levels of GK in homozygous mutant (Mut) hepatocytes. Data are presented as percentage of wild-type (WT) hepatocytes. (D) Densitometric quantitation of the Western blot of extracts from cells grown for an additional 6 hr in the presence or absence of cycloheximide showing absence of altered levels of GK degradation in Mut hepatocytes. GK values in WT and Mut cells, cultured in the absence of cycloheximide at time 0, were both considered as 100%, and data are presented as a percentage of these values.