The upregulation of Bim mRNA expression decreased over time, and by 8 months of age, Bim expression levels had returned to baseline in RET/PTC3 Dicer1(+/+) and RET/PTC3 Dicer1(+/−) thyroid tumors, reaching values comparable to those observed in the WT condition. The gene discussed is DICER1; the disease is thyroid tumor.