MA203 is a highly efficient and selective PROTAC degrader targeting CHK1. MA203 accelerates CRBN-dependent proteasomal degradation of CHK1 in solid tumor-derived cells and acute leukemia cells. MA203 induces DNA replication stress. MA203 blocks cell cycle progression and triggers tumor cell apoptosis. MA203 does not damage healthy differentiated and primitive hematopoietic cells, stromal cells, and retinal epithelial cells. MA203 can be used for the study of CHK1-dependent cancers[1].