Focusing on RAD17, we show in clonogenic assay that shRNA mediated knockdown of RAD17 increases the sensitivity of either HeLa or LN428 cancer cells to both chemical inhibition or siRNA mediated knockdown of the checkpoint kinases CHEK1, CHEK2 and WEE1. Evidence of the interaction between RAD17 and CHEK1/2 was also seen in a functional genomic screen involving a panel of over 100 cell lines and in the budding yeast S. cerevisiae. This evidence concerns the gene CHEK1 and cancer.