PTEN and breast cancer: PTEN also plays an important role in the regulation of T cells, and it has been demonstrated that EV-associated miR-214 from a range of tumour cells including breast cancer, hepatocellular carcinoma, non-small-cell lung cancer (NSCLC) or pancreatic cancer could transfer to T cells leading to downregulation of PTEN and promoting T-reg (regulatory T cells) expansion and IL-10 (interleukin-10) secretion, which in turn promotes tumour growth and enhanced immune suppression in vivo [94].