SMN1 and head and neck squamous cell carcinoma: Similar to TGF-β1-treated HFFF2, SMA-positive cells generated through senescence were contractile (Fig. 2H) and supported Transwell migration of tumor cell lines from cancers of the head and neck (HNSCC, 5PT) and esophagus (EAC, OE33) (Fig. 2I).