If indeed Bid proapoptotic function is compromised, an attractive theory to explain increased metastatic potential may be the increased ability of tumour cells with reduced Bid function to avoid Fas/TNFR/Granzyme B-mediated apoptosis, induced by immune cells circulating in the body, thus enabling malignant cells to invade surrounding tissue early in tumour development. The gene discussed is BID; the disease is neoplasm.