APOBEC3B and cancer: The A3B staining intensity and distribution showed inter‐ and intratumoral heterogeneity, a finding in agreement with A3B staining pattern in other human cancers, i.e. HPV‐positive and HPV‐negative head/neck squamous cell carcinoma33 and clear‐cell ovarian carcinoma34 that also exhibit increased, overall, A3B staining and the prevalence of APOBEC3 mutation signatures SBS2 and SBS13.