EGFR and lung carcinoma: Third, a number of studies, in both lung cancer cells and other cells, report that activation of EGFR1/HER1, HER2, and HER3 results in stimulation of the MAPK cascade, as well as activation of the PI3K/AKT pathway, each of which can have an important effect on cell behavior (growth, migration, apoptosis, and biological response).