SP1 and head and neck squamous cell carcinoma: Sp1 is a transcription factor that has been linked to both the acquisition of stem‐like properties and the resistance to radiotherapy, through the alteration of the DNA damage response (DDR) in different types of cancer, including HNSCC (Olofsson et al,2007; Beishline et al,2012; Tschaharganeh et al,2014; Zhang et al,2014; Beishline & Azizkhan‐Clifford, 2015; Liu et al,2016; Xu et al,2017; Fletcher et al,2018).