CHRNB4 and head and neck squamous cell carcinoma: Additionally, the co-expressed genes (e.g., ARNT and NOTCH) of CHRNB4 in the CHRNB4-high group (pink) and the gene FLT4 in the CHRNB4-low subgroup (orange) were involved in HIF-1 and Notch signalling pathways, which promote angiogenesis and migration in smoking HNSCC patients.