Human papillomavirus (HPV) has been classified as one of the causing factors of head and neck squamous cell carcinoma (HNSCC). However, little is known about HPV-related carcinogenesis in HNSCC. The purpose o f this s tudy i s to characterize immortalized human oral keratinocyte (IHOK) transfected by HPV16 E6/E7, IHOK/hcdk4 (IHOK transfected by pLXRN-hcdk4) and IHOK/hcdk4/hTERT (IHOK transfected by pLPC-hTERT-hcdk4) to reconstitute HNSCC in vitro. Conclusively, we established a new immortalized cell lines, IHOK/hcdk4 and IHOK/hcdk4/hTERT, to understand multistep carcinogenic process of oncogenic HPV16 E6/E7 in HNSCC.