MAPK3 and neoplasm: The exosome is identified as a kind of micro-vesicle that is derived from a wide variety of cells and can act as a membrane fragment with a size of approximate 60–120 nm.29, 30 Furthermore, exosomes are composed of different subsets of miRNAs that are dependent on the cell type from which they are secreted.31 According to Zhu et al.,32 by triggering the extracellular signal-regulated kinase 1/2 (ERK1/2) pathway, ADMSC-exosomes increased the expression of vascular endothelial growth factor (VEGF) in tumor cells, thus leading to tumor growth in vivo.