DUSP4 and depressive symptom measurement: For example, cg12721804, which is hypermethylated in affected twins (Δβ = +.06, p = .001), is located in the last exon of DUSP4 (also known as mitogen-activated protein kinase phosphatase 2), which has been shown to be unregulated in the brains of individuals with depression who committed suicide (34).