Checkpoint kinase 1(Chk1)is a serine/threonine kinase that mediates cell cycle arrest in S-phase or at the G2/M transition.Inhibition of Chk1 would abrogate these checkpoints so that cancer cells,when suffered damage from chemical drug or radiation,would enter mitosis without self-repair,eventually leading to cell death or apoptosis.Therefore,this kind of inhibitor has potential to work as sensitizing agents in cancer therapy.