Bladder cancer cells that have internalized BCG secrete various immune-activating effectors, including interleukin (IL)-6, IL-8, granulocyte-macrophage colony-stimulating factor (GM-CSF) and tumor necrosis factor (TNF)-α [21,22,23,24], hinting at a possible mechanism in which internalization of BCG by bladder cells leads to recruitment or activation of immune cells. Here, TNF is linked to urinary bladder cancer.