MAP2K1 and lung adenocarcinoma: GR inhibits the GRB2-RAF-MEK1 pathway (GRB2 = growth factor receptor bound protein 2; RAF = RAF Proto-Oncogene Serine/Threonine-Protein Kinase; MEK1 = Mitogen-Activated Protein Kinase Kinase 1) in A549 cells, a human lung adenocarcinoma cell line, by blocking GRB2 recruitment, preventing its association to phosphorylated EGFR and subsequent downstream signaling [22].