ALDH1L1 and head and neck squamous cell carcinoma: We performed multicolor immunohistochemical staining on human HNSCC tissues and mouse tongue orthotopic tumor model tissues, and found colocalization of Aldh1l1 and S100 (a marker primarily expressed in Schwann cells), indicating that Aldh1l1 is expressed in glial cells of the tongue (Supplementary Fig. 5A, B).