MAPK1 and pancreatic neoplasm: EGFR has also been shown to be required for tumorigenesis in a K-Ras(G12D) pancreatic cancer model, and ablation of EGFR leads to ∼2-fold reduction of downstream levels of Ras-GTP and phosphorylated ERK (herein referring to ERK1 and ERK2, also known as MAPK3 and MAPK1, respectively) (Ardito et al., 2012).