FUCA1 and thyroid gland undifferentiated (anaplastic) carcinoma: The same trend was observed in thyroid cancer patients, as follows: FUCA1 RNA expression is high in papillary thyroid cancers (PTCs) which mostly carry wild-type p53, while low levels of FUCA1 RNA were detected in anaplastic thyroid cancers (ATCs) where p53 is frequently mutated.