DIRAS1 and esophageal squamous cell carcinoma: Aberrant hypermethylation of CpG islands in the promoter region of DIRAS1 is identified by bisulfite sequencing in renal cell carcinoma cell lines (ACHN, 786-O and Caki-1).6 Hypermethylation of the DIRAS1 promoter region and the resulting deletion or reduction of DIRAS1 expression have also been identified in colorectal cancer samples, esophageal squamous cell carcinoma tissues, and corresponding cell lines.8,10