ALDH1A1 and head and neck squamous cell carcinoma: Quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) and Western blot showed that the expression of CD24, BMI1, SOX2, ALDH1, and OCT4, which are well-known genes associated with HNSCC CSC-characters [12], were increased in the ALDHhigh CSC-like cells (Fig. 1B and Supplemental Fig. S1A).