Quantitation of IHC marker-positive cell density in tumor and tumor-associating stroma in spontaneous Stat1-null tumors (Additional file 2: Figure S9) indicated tumor-infiltrated F4/80+ cells were at a significantly (p < 0.0001) lower density (6 cells/mm2, SE = 2) than the cellular density in the stroma (2580 cells/mm2, SE = 473). This evidence concerns the gene STAT1 and neoplasm.