PLXNB1 and head and neck squamous cell carcinoma: A recent study indicated that SEMA4D is induced by hypoxia in a HIF-1 dependent manner and influences tumor vascularity in head and neck squamous cell carcinoma (HNSCC) [10] in a manner analogous to VEGF in order to attract Plexin-B1-expressing endothelial cells into the tumor for the purpose of promoting growth and vascularity.