BCR and chronic myelogenous leukemia, BCR-ABL1 positive: As indicated in our published in vitro study, the de novo transcription of BCR/ABL DNA transferred by K562 EVs plays an important role in the pathogenesis of CML [4], Therefore, we examined the expressions of BCR/ABL DNA, mRNA, and protein in the peripheral blood of NOD/SCID mice injected with K562 EVs or K562 cells and found them to be expressed in their neutrophils (Figure 4).