MAPK3 and breast cancer: In breast cancer cells, the paracrine role of epidermal growth factor (EGF) and its receptor EGFR (ErbB-1) contribute to invasion, intravasation, and metastasis [68] through activation of extracellular signal-regulated kinase 1/2 (ERK1/2), STAT3, or PI3K/Akt signaling, promoting the EMT [69,70,71].