This study led to tumor necrosis factor alpha (TNFa) and IL-2 to be chosen and inserted into an oncolytic adenovirus, with mutations for cancer cell selectivity (E2F tumor-specific promoter, D24 deletion in the E1A gene) and enhanced cancer cell entry by knob protein exchange (Ad5 knob was exchanged to serotype 3 knob). Here, TNF is linked to cancer.