We have previously demonstrated by microarray analysis that S100A4 was highly expressed in anaplastic thyroid carcinoma cell line with high metastatic potential (ARO/met2) as compared to its parental cell line ARO and found that S100A4 overexpression was associated with advanced disease stage (Zou et al, 2004). This evidence concerns the gene S100A4 and thyroid gland undifferentiated (anaplastic) carcinoma.