DBF4 and oral cavity squamous cell carcinoma: Our results showed that most of oral cancer-derived cells had a higher protein level of Cdc7-Dbf4 and ATR-HSP90-HCLK2 complex than normal human oral keratinocytes (HOK) (Fig. 6A), suggesting that Cdc7-Dbf4 and ATR-HSP90-HCLK2 complex are overexpressed in Oral Squamous Cell Carcinoma (OSCC).