Immunoprecipitation of HER3 also showed that wortmannin lowered the polyubiquitination of HER3 in both control SCCHN cells and the corresponding NOTCH1-knockdown counterpart, and the polyubiquitination of HER3 was more prominent in NOTCH1-knockdown cells than that discerned in the control cells (Fig. 3B). Here, NOTCH1 is linked to head and neck squamous cell carcinoma.