SCH900776 S-isomer is primarily utilized in research settings as a selective inhibitor of CHK1 (Checkpoint kinase 1). Its application is significant in the study of cancer biology, particularly in understanding the role of CHK1 in DNA damage response and cell cycle regulation. By inhibiting CHK1, researchers can explore its effects on cancer cells, especially in combination with DNA-damaging agents or radiation therapy, to enhance the efficacy of these treatments. This compound is also used to investigate mechanisms of chemoresistance and to develop strategies for sensitizing tumor cells to chemotherapy. Its role in preclinical studies helps in identifying potential therapeutic approaches for various cancers.