H2AX and breast cancer: However, Dutta et al. showed that EVs isolated from the cell culture supernatant of human breast cancer cell lines were able to induce phosphorylation of key proteins (ataxia-teleangiectasia mutated (ATM), H2AX, Chk1, and p53) involved in DNA damage response in primary mammary epithelial cells in vitro by transmitting signals that led to ROS production and a consequential oxidative stress in the EV-recipient cells (54, 55).