To further unravel the complex involvement of synemin in the regulation of radiation survival, we performed synemin knockdowns using three different siRNAs and one esiRNA (endoribonuclease-prepared siRNA) in two 3D lrECM grown HNSCC cell lines, i.e., Cal33 and SAS (Figure 1A–F and Figure S1A,B). The gene discussed is SYNM; the disease is head and neck squamous cell carcinoma.