Fig. (4) Graphical representation of the genes that were differentially expressed in at least two studies reporting the differential expression between HPV-positive versus HPV-negative head-and-neck cancers. The signatures represent the differentially expressed genes as follows: Schlecht_HNSC [49] and Slebos_HNSC [47], HPV-positive versus HPV-negative head-and-neck squamous cell carcinoma; Martinez_oropharyngeal [48], HPV-positive versus HPV-negative oropharyngeal squamous cell carcinoma; Pyeon_HPV_positive_cancers [50], HPV-positive head-and- neck cancer (HNC) and cervical cancer versus HPV-negative HNC. The upregulated genes are depicted in orange, downregulated in green, and not differentially expressed in white. The annotations of the genes are included as Supplementary Table 1.