To further validate that the observed complement activation was not related to apoptosis, we performed a double stain with Annexin V and TCC, and while most cells were negative for Annexin V staining, we found faint annexin V staining in cells with normal nuclear morphology (Fig. 1e) in HNSCC cell line (HN8), but cells stained with Annexin V showed less TCC staining, and the staining did not colocalize with TCC as C3 often does (Fig. 1a), further emphasizing that complement activation is not associated with phosphatidylserine or apoptotic cells. Here, SFXN1 is linked to head and neck squamous cell carcinoma.