TP53 and neoplasm: Indeed, we observed a robust uptake of fluorescent RAS-3-derived EVs by immortalized fibroblastic cell lines of rat (RAT-1 and RAT-2) and mouse (NIH3T3) origin, and by primary cultures of mouse embryonic fibroblasts from p53-deficient mice (MEFp53−/−) (Figure 3A), all of which lack tumor suppressor mechanisms and are susceptible to oncogenic transformation [31].