CHEK1 and lip and oral cavity carcinoma: We found that siRNA-mediated RBM17-knockdown of the cell lines gained a significantly higher sensitivity to 5-FU, which was remarkably followed by a decrease in the expression of checkpoint kinase 1 (CHEK1) protein, whereas treatment with a CHEK1 inhibitor did not affect RBM17 protein expression in the oral cancer cell lines.