EGFR and head and neck squamous cell carcinoma: Interestingly, another HER/ErbB family surface receptor, ErbB2, was also affected by hDT806 treatment in HNSCC, showing a significant decrease in ErbB2 protein levels, by 65.8 ± 9.9% (Figure 2(Ab,Cb); Figure S3A) in JHU-029 and 40.2 ± 7.3% (Figure 2(Bb,Db); Figure S3B) in JHU-022, respectively.