PRNP and breast cancer: As expected, our in vitro study demonstrated that, when compared to the control (i.e., SV-HUC-1 cell line), the protein levels of PI3K-Akt-mTOR-MMP9 signaling were markedly upregulated in BC cells (i.e., T24 cell line), more upregulated in PrPC-OE-T24 cells, significantly suppressed in PrPC-silencing T24 cells, and also markedly downregulated in PrPC-OE-T24 cells treated with a PI3K inhibitor.