MAPK3 and breast cancer: Significantly increased autophagic activity was observed in trastuzumab-resistant SKBR3 and JIMT1 breast cancer cells bearing HER2 amplification, where it correlated with the downregulation of AKT and Extracellular Signal-Regulated Kinase 1 (ERK1)/ Extracellular Signal-Regulated Kinase 2 (ERK2) signaling during early treatment [165].