In our previous report [32] and the present study, MDA-MB-231-EV-injected mice showed a high number of cancer cells that had invaded into the lungs (9 of 10 mice), however, this was also seen in 3 of 10 mice injected with MDA-MB-231-P2Y2R-shRNA (Figure 6D) (P = 0.018, Fisher’s exact test). This evidence concerns the gene P2RY2 and cancer.