MAPK3 and cancer: It was reported that tumour aggressiveness may be related to the accumulation of proteins involved in tumourigenesis, such as phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K), extracellular signal-regulated kinase 1 and 2 (ERK1 and ERK2), and caveolins in the lipid droplets of different cancer cells [59,60,61].