KRAS and neoplasm: In fact, it has been well documented in the genetically engineered KPC (Kras LSL-G12D/+Trp53LSL-R172H/+ Pdx-Cre) and KC mouse (KrasLSL-G12D/+ Pdx-Cre) models, that KRAS mutations in PanIN lesions associate with inflammatory environments with overexpression of COX2 (42), and early infiltration of T regulatory cells (Tregs), Tumor associated macrophages (TAMs) and Myeloid derived suppressor cells (MDSCs).