EGFR and cancer: Morphine-induced activation of the μ-opioid receptor led to an increase in the expression of the epidermal growth factor receptor (EGFR), which caused an increase in proliferation in vitro of human non-small cell lung cancer (NSCLC) cell lines through phosphorylation of MAPK, ERK, and protein kinase B, which are responsible for triggering the synthesis of proteins involved in the proliferation, migration, and epithelial-mesenchymal transition of cancer cells [10].