Third, PyMT-induced β-cell hyperplasia has a low proliferation index (as judged by Ki67 staining: 3.7±1.5%), compared to acinar cell carcinomas (46.7±12%), Tag-induced β-cell hyperplasia (21.1±3%; data not shown), and Myc-induced β-cell hyperplasia (near 100%) [26]. The gene discussed is MKI67; the disease is acinar cell carcinoma.