DIRAS1 and esophageal squamous cell carcinoma: DIRAS-1, in contrast to common oncogenic small GTPases like Ras or Rho family members [3], has been reported as a potential tumor suppressor in human glioblastoma [2], colorectal cancer [4], renal cell carcinoma [5], and ovarian cancer [6], and reduced expression of DIRAS-1 predicts poor prognosis in esophageal squamous cell carcinoma [7].