DDX5 and head and neck squamous cell carcinoma: Polyubiquitination of DDX17 at Lys190 mediated by the E3 ligase HectH9 under hypoxia interacts with YAP and p300 to enhance the transcription of stemness-related genes and tumor-initiating capabilities in head and neck squamous cell carcinoma, while DDX5 does not contain the Lys residue corresponding to Lys190 on DDX17 and consequently fails to bind to YAP [41].