CAV1 and neoplasm: In addition, we stained for MMP14, which was one of the highest upregulated genes in both the HPV-negative and HPV-positive TCGA-HNSC subcohorts, performed the same analysis as for CAV1, and observed similar results with a strong association of increased MMP14 expression in the tumor buds in both the HPV-negative and HPV-positive subcohorts (Supplementary Fig. 7).