PHF5A and head and neck squamous cell carcinoma: Moreover, we downregulated the expression of PHF5A by transfecting two siRNAs targeting PHF5A into HNSCC JHU011 and Tu686 cells, upregulated the expression of PHF5A by stable transfection of PHF5A cDNA into HNSCC FaDu cells, and found that following downregulation or upregulation of PHF5A in HNSCC cells, the expression of the DOCK5 variant was also significantly decreased or increased correspondingly, with only a modest effect on DOCK5 wild-type gene expression (Fig. 1C).