Stable cancer cell lines derived from human cancers are very useful models to predict clinical response of new therapeutics. Schweppe et al. (2) evaluated 40 reported thyroid cancer-derived cell lines using short tandem repeat and single nucleotide polymorphism array analysis. They found some misidentified cell lines. The ARO matched the HT-29 colon cancer cell line, and NPA matched the M14/MDA-MB-435S melanoma cell line.

The report of Schweppe et al. (2) was available online at August 2008, two and half years earlier than the submission date of paper from Kang et al. (1). Kang et al. (1) showed that quercetin did not induce NIS in ARO cell and induced NIS very slightly in NPA cells. These results make sense because ARO and NPA cells are not originated from the thyroid.

Careful choice of thyroid cancer cell lines with unique source is crucial. Ringel (3) recommended researchers to establish if the cell lines in their laboratories are either thyroid or unique by comparing them with the data in the paper by Schweppe et al. (2).