ACTA1 and head and neck squamous cell carcinoma: The advent of single cell transcriptomic sequencing (scRNA-seq) is beginning to characterise CAF heterogeneity within HNSCC and other cancers, and it is now accepted that not all CAF subpopulations are characterised by high expression of α-SMA, and conversely, not all α-SMA-positve CAF are myofibroblastic.