DICER1 and thyroid tumor: On the other hand, the WT allele (478 bp) was present in the follicular cells from WT thyroids and RET/PTC3 Dicer1(+/−) and RET/PTC3 Dicer1(+/+) thyroid tumors, as expected, but also in RET/PTC3 Dicer1(−/−) thyroid tumors.