IL6 and obesity due to melanocortin 4 receptor deficiency: In mouse models of oncogenic Kras-driven PDAC, obesity (HFD and Lepob/ob induced) enhanced immune cell infiltration (predominantly myeloid cells including macrophages and neutrophils), pro-inflammatory cytokine expression (TNFα, IL-6, IL1β), and fibrosis (sirius red staining and αSMA+ myofibroblasts) in the microenvironment of emerging tumors (Khasawneh et al, 2009; Dawson et al, 2013; Philip et al, 2013; Incio et al, 2016a; Chang et al, 2017; Chung et al, 2020).