TGFBR2 and neoplasm: Partial TβRII KO fibroblasts were used due to their ability to invoke more aggressive tumor behavior as compared with that of pure TβRII KO fibroblasts or TβRII competent fibroblasts [16]; however, each of these fibroblast cell lines were tested in our chicken embryo model and produced similar tumor migratory phenotypes as described below (data not shown).