HIF1A and head and neck squamous cell carcinoma: Figures 6(a) and 6(d) shows the representative tumor vascular distribution (arrow, brown) in poorly and well differentiated HNSCC with regions of hypoxia stained for CAIX immunostaining (Figures 6(b) and 6(e)) and HIF-1α (Figures 6(c) and 6(f)).