Viruses, such as the Kaposi's sarcoma-associated herpes virus (KSHV), can confer apoptosis resistance and tumor progression by expression of vFLIP isoforms that resemble cFLIPS (Punj et al., 2009) and are upregulated during late stages of KHSV-induced sarcoma (Sturzl et al., 1999). This evidence concerns the gene CFLAR and sarcoma.