CD274 and neoplasm: Interestingly, differences in the dynamics of EV secretion were observed between models, with both tumor cell- and fibroblast-derived PD-L1+ EVs being high at day 3 but declining at days 6 and 12 within the p53 null (H358) model compared to the p53 wild-type model (A549), which showed stable levels of derived PD-L1+ EVs throughout culture.