STING1 and head and neck squamous cell carcinoma: To establish a link between the formation of MN representing membrane-bound cytosolic DNA fragments and activation of the cGAS/STING pathway in HNSCC cells, we examined the integrity of MN and the recruitment of cGAS using immunolabeling and fluorescence microscopy in a modified cytokinesis block micronucleus (CBMN) assay (Figure 3C,D).