Tissue microarray analysis revealed that although both ISG15 and HMGCR were highly expressed in pancreatic cancer, their expression displayed a mutually exclusive pattern: tumor cells with elevated ISG15 exhibit low HMGCR levels, and conversely, HMGCR-high cells show minimal ISG15 expression (Fig. 2A). The gene discussed is HMGCR; the disease is familial pancreatic carcinoma.