Since phosphorylation at the tyrosine residue at position 701 synergizes with that at the serine residue at position 727 of STAT1 to effect the maximal transcriptional activity [53,55], two STAT1 mutants, one lacking the Tyr residue (Y701F) and one lacking the Ser residue (S727A), were tested for their ability to induce tumor cell death. Here, STAT1 is linked to neoplasm.