In a landmark study, Hickman et al. showed by quantitative PCR that in PS1-APP mice, an established mouse model of AD, microglia had a 2.5-fold increase in levels of the proinflammatory cytokines interleukin 1β (IL1β) and tumor necrosis factor TNFα, suggesting that there is an inverse correlation between cytokine production and Aβ clearance [96]. The gene discussed is TNF; the disease is Alzheimer disease.