Oncol Rep 15: [Related article:] 329–334, 2006; DOI: 10.3892/or.15.2.329 After the publication of the article, the authors noted that the relevance of the findings reported in this article on IDN5109 inhibition of growth of head and neck squamous cell carcinoma (HNSCC) is now in question. To examine the antitumor effect of IDN5109, this study was conducted using YCU-H891 and KCC-MS871 cell lines that the authors believed to be HNSCC cell lines. Because different human leukocyte antigen (HLA) was detected in 2 cell lines (KCC-TCM901 and KCC-T873) which were derived from the same patient in an experiment after publication, 16 cell lines established in our institution were analyzed by short tandem repeat (STR) analysis. STR analysis revealed that genotype of KCC-TCM901, YCU-H891 and KCC-MS871 was identical to that of HeLa cells, and that genotype of YCU-T891 was identical to that of YCU-L891, which was considered to be cross-contamination.