CD44 and head and neck squamous cell carcinoma: Moreover, we showed that p53-target genes such as CDKN2A, NOTCH1 and PCNA, were up-regulated in HPV+ HNSCC patients, however, CAV1, CD44, and RTN4 were up-regulated in HPV- HNSCC, suggesting that changes in these markers are expected to disturb the cell cycle and facilitate carcinogenesis either directly or indirectly in the HPV-associated HNSCC.