No mutations were detectable, indicating that at least in these cases, mammary tumors did not expand because of a mutation in STAT1. We have further analyzed mRNA expression of STAT1 and its target gene IRF1 in paired samples of tumor and adjacent tumor-free tissue and found a significant increase in expression of both genes in neoplasm rather than a decrease (Figure 3A). This evidence concerns the gene STAT1 and neoplasm.