ACTA1 and head and neck squamous cell carcinoma: The IB results showed that compared with the conditioned medium (CM) of normoxic HNSCC cells, the hypoxic tumor cells-derived CM (hCM) markedly improved the expression of α-SMA in NFs; while the removal of exosomes from hCM severely limited the increase (Fig. 3C and Supplementary Fig. 6A), which implied that hypoxic HNSCC-derived exosomes might play a prominent role in converting NFs to CAFs.