Direct effects on cancer cells may also synergize with cancer-directed therapies, as was the case with Klebsiella pneumoniae bEVs that enhanced the anti-cancer properties of tamoxifen in MCF-7 cells via the activation of Cyclin E2 and pERK signaling, which resulted in inhibition of cancer cell proliferation in vitro [115]. This evidence concerns the gene CCNE2 and cancer.