APOB and head and neck squamous cell carcinoma: Conversely, the contribution of signatures associated with the apolipoprotein B mRNA–editing enzyme catalytic polypeptide-like (APOBEC) (SBS 2 and SBS 13) was relatively low in V-negative and EBV-positive tumors and high in HPV-positive HNSCC (P = 8.2 × 10–6) (Figure 2C), as previously reported (24, 25).