HNF4A and type 2 diabetes mellitus: HNF-4α repressed PEA-15 expression in HeLa cells and HNF-4α silencing correlated with PEA-15 overexpression resulting in a significant reduction in hepatic glycogen content which could account for the elevated expression levels witnessed in type 2 diabetes (Ungaro et al., 2008, Ungaro et al., 2010).