TGFBR1 and neoplasm: As this may have been due to the PK of the antibody in the tumor, we generated mouse models of BRAFV600E-PTC with thyroid-specific knockout of the TgfβR1 gene, TPO-Cre/LSL-BrafV600E/TβR1fl/fl (Braf/TβR1) or, to avoid confounding effects of loss of the receptor during development, through post-natal dox-inducible expression of a TβR1 shRNA.