PRMT5 and head and neck squamous cell carcinoma: We also examined the protein levels of PRMT5 and ΔNp63α in HNSCC patient samples, which revealed that PRMT5 and ΔNp63α were co-expressed within the proliferative basal layer of the stratified squamous epithelium of the tumors; this cell population consisted of less-differentiated basal-like cells (Figure 1D).