Figure 3

Pancreatic islets from two pIns-c-MycER ^TAM / Bcl-x _L transgenic mice following activation, inactivation, and then reactivation of c-MycER ^TAM (c-Myc). Paraffin-embedded fixed sections of pancreata from c-MycER ^TAM/Bcl-x _L mice were examined histologically by H&E staining. Activation of c-Myc for 14 days by daily IP injection with 4-OHT was followed by subsequent inactivation of c-Myc for 9 days by withdrawing 4-OHT, and then reactivation of c-Myc for 14 days results in further progression of the neoplastic phenotype -c-Myc on-off-on (2 weeks). Extending the period of c-Myc reactivation results in further expansion of the tumour mass, marked dysplasia and invasion.