SMYD3 and head and neck squamous cell carcinoma: To further validate the presence of SMYD3 in the nucleus of HPV-negative HNSCC cancer cells, nuclear/cytoplasmic protein extraction in 6 HPV-negative HNSCC cell lines followed by Western blotting for SMYD3 was conducted to compare the protein expression levels of SMYD3 in the nuclear and cytoplasmic compartments across these cell lines.