TP53 and esophageal squamous cell carcinoma: Loss of p53-mediated repression of APOBEC3B transcription, resulting either from TP53 mutation (observed at high frequency in HPV-negative HNSCC and ESCC) or from HPV E6/E7 activity in HPV-positive HNSCC (Vieira et al, 2014; Periyasamy et al, 2017) is also likely an important driver of APOBEC3B expression seen in many of the SCC samples we analysed.