Figure 3

Real-time imaging of p16^INK4a expression during skin papilloma development. The p16-luc mice were subjected to a conventional chemically induced skin papilloma protocol with a single dose of DMBA followed by multiple treatments with TPA. This protocol causes an oncogenic mutation in the H - ras gene. Benign skin papillomas began to appear after 7 weeks of DMBA treatment, and continued to grow until 20 weeks or so. However, after that, most papillomas stop growing. So we classified these growing papillomas as the early stage papilloma and non-growing papillomas as the late stage papillomas. The p16-luc mice were subjected to noninvasive BLI, and the significantly elevated bioluminescent signals were detected in the late stage papillomas. The color bar indicates photons with minimum and maximum threshold values.